Patent Grant
9981484
This disclosure is directed to systems and methods for applying flame treatments to objects, and, more particularly, to systems and methods for applying flame treatments to print surfaces of objects in inkjet printing systems.
Flame treatment processes for various products in industrial manufacturing settings are known to the art. In particular, some types of materials including polymers benefit from being exposed to flame prior to receiving additional coatings including, for example, ultraviolet (UV) curable inks and other suitable coating materials that are applied using an inkjet printing system. The flame treatment process alters the surface of the polymer material to promote adhesion and spreading of the ink on the surface of the object. After an object has received the flame treatment in a specialized flame treatment system, the object later receives one or more additional material coatings in a separate coating system. For example, inkjet printing systems that are known to the art form printed ink images and coatings on the three-dimensional surfaces of different objects to provide monochrome and multi-color text and graphics, and transparent protective coatings to the objects.
While the benefits of flame treatment processes are generally known to the art, existing flame treatment systems cannot be used in many practical situations because these systems are specifically designed for large scale manufacturing in industrial settings. For example, one flame treatment system that is known to the art employs a robotic arm that passes a liquefied petroleum gas torch over various objects in a carefully controlled environment within an industrial-scale manufacturing process. These flame treatment systems can be effective in industrial settings for high-volume mass production of different items that receive flame treatments as part of a manufacturing process. However, the underlying technology that is used in the industrial scale manufacturing processes is also incompatible with newer “on-demand” manufacturing devices such as the inkjet printers that are used in small retail spaces and other environments that lack the infrastructure to support existing flame treatment systems. The existing flame treatment systems cannot be combined with these inkjet printers because the existing flame treatment systems consume large amounts of hydrocarbon fuels such as liquefied petroleum gas, propane, and natural gas. These systems are impractical for use with a self-contained inkjet printer. Consequently, improvements to flame treatment systems that are suitable for integration into inkjet printers would be beneficial.
In one embodiment, a method for applying flame treatment to a print surface in an inkjet printer has been developed. The method includes activating a hydrogen torch within the inkjet printer to generate a flame through a nozzle of the hydrogen torch, operating an actuator to move at least one of the print surface or the nozzle in a predetermined direction to apply the flame from the nozzle to the print surface, and adjusting, with a controller and at least one valve in the hydrogen torch, a rate of fuel flow to the nozzle of the hydrogen torch to change a thermal output level of the flame with reference to a change in distance between the nozzle of the hydrogen torch and the print surface during the operating of the actuator.
In another embodiment, an inkjet printer that applies flame treatment to a print surface of an object has been developed. The inkjet printer includes a housing, a part holder positioned with the housing, the part holder being configured to hold an object, a hydrogen torch positioned within the housing, an actuator positioned with the housing and operatively connected to at least one of the hydrogen torch and the part holder, and a controller operatively connected to the hydrogen torch and the actuator. The hydrogen torch includes a nozzle configured to emit a flame generated by the hydrogen torch and at least one valve configured to adjust a rate of fuel flow to the nozzle. The controller is configured to activate the hydrogen torch to generate the flame through the nozzle of the hydrogen torch, operate the actuator to move at least one of the print surface or the nozzle in a predetermined direction to apply the flame from the nozzle to the print surface, and adjust the rate of fuel flow to the nozzle of the hydrogen torch with the at least one valve to change a thermal output level of the flame with reference to a change in distance between the nozzle of the hydrogen torch and the print surface during the operation of the actuator.
The foregoing aspects and other features of an inkjet printer that applies flame treatments to print surfaces are explained in the following description, taken in connection with the accompanying drawings.
For a general understanding of the environment for the embodiments disclosed herein as well as the details for the embodiments, reference is made to the drawings. In the drawings, like reference numerals designate like elements.
As used herein, the term “hydrogen torch” refers to a device within an inkjet printer that generates a flame via the combustion of hydrogen (H2) and oxygen (O2) molecules. The byproducts of the combustion are heat and water (H2O), which is typically generated in the form of water vapor. In the embodiments described herein, the hydrogen torch includes an electrolysis system that generates the hydrogen and oxygen for combustion by application of electricity to water that is mixed with an electrolyte such as sodium bicarbonate or another suitable electrolyte.
In an inkjet printer, the hydrogen torch generates the heat to perform a flame treatment process on a surface of an object prior to operation of one or more inkjet printheads in the printer to form a printed image on the surface of the object. As used herein, the term “print surface” refers to the surface of the object that receives the flame treatment and the ink drops that form the printed image. Objects that are formed from various materials that are suitable for receiving a flame treatment prior to a printing operation include, but not limited to, polyolefin polymers including polyethylene (PE), high-density polyethylene (HDPE), polypropylene (PP), polymethylpentene (PMP), and polybutene-1 (PB-1) thermoplastics. The flame treatment improves the degree of spreading and adhesion of individual ink drops in the printed image to the print surface, which improves the quality of printed images by reducing or eliminating streaking and smudging of the ink drops in the printed image.
In the printer 100, the part holder 114 is depicted as a flat tray that supports the object 160 to enable the torch nozzle 106 to apply a flame treatment to a print surface on the object 160 and for the inkjet printhead 120 to eject ink drops onto the print surface. In other embodiments, the part holder 114 includes clamps, vacuum suction orifices, and other attachment mechanisms that hold the object 160 securely in place during operation of the printer 100. Additionally, in some embodiments the part holder 114 orients the object 160 about a rotational axis of the object 160 within the printer 100 with only a base or other non-printed surface of the object 160 being directly attached to the part holder 114. This configuration enables the printer 100 to apply flame treatments and printed images in an “all around” printing operation on many common objects such as cups, pens, cases, and any other object that receives a printed image that wraps around multiple sides of an object.
In the illustrative embodiment of
In the illustrative embodiment of
In the printer 100, the controller 128 is a digital logic device such as a microprocessor, microcontroller, field programmable gate array (FPGA), application specific integrated circuit (ASIC) or any other digital logic that is configured to operate the printer 100. The controller 128 is operatively connected to the hydrogen torch 104, the displacement sensor 108, the inkjet printhead 120, either or both of the actuators 124A/124B, and the user interface device 150. The controller 128 is also operatively connected to a memory 132. In the embodiment of the printer 100, the memory 132 includes volatile data storage devices, such as random access memory (RAM) devices, and non-volatile data storage devices such as solid-state data storage devices, magnetic disks, optical disks, or any other suitable data storage devices. The memory 132 stores programmed instruction data 136, a database including either or both of two-dimensional print surface area and three-dimensional profile data 140, and image data 144 that the controller 128 uses to operate the inkjet printhead 120 to form printed images on the print surface of the object 160 or other objects. The controller 128 executes the stored program instructions 136 to operate the components in the printer 100 to apply a flame treatment to the print surface of the object 160 and to form printed images on the print surface of the object 160.
In the memory 132, the two-dimensional area data 140 include, for example, an aggregate two-dimensional surface area for a print surface of a three-dimensional object. The three-dimensional profile data 140 include the total two-dimensional area for the print surface and further include a set of depth information for different regions of the area that provides information for both the total area in two-dimensions and the three-dimensional data corresponding to the distance between the nozzle 106 and the print surface over different portions of the print surface. In some configurations, the controller 128 uses either the two-dimensional area data or the three-dimensional profile data to generate an estimate of the amount of hydrogen and oxygen fuel that the hydrogen torch 104 consumes during the flame treatment process of the print surface. The two-dimensional area data are simpler to process but provide an estimate of fuel consumption that may be less precise since the printer 100 adjusts the level of fuel consumption for the hydrogen torch based on the distance between the nozzle 106 and the print surface on the object, which often varies during the flame treatment process. The three-dimensional profile data can enable the controller 128 to generate a more precise estimate of fuel consumption for the flame treatment process but require more complex computations to produce the estimate. Either embodiment is suitable for use with the printer 100.
In
In the hydrogen torch 104, the pumps 332 and 336 extract the H2 gas and O2 gas, respectively, from the electrolytic cell 324. The pump 332 delivers the H2 gas to an inlet of first storage tank 340 and the pump 336 delivers the O2 gas to an inlet of a second storage tank 344. Each of the storage tanks 340 and 344 includes a relief valve to vent gas to the atmosphere in the event that the pressure levels of the gas exceed the operating pressure of the tanks. In some embodiments, each of the tanks 340 and 344 includes a pressure sensor that enables an external controller, such as the controller 128 in the printer 100, to monitor an amount of gas that is stored in each tank based on the pressure level within the tank. As described above, the electrolytic cell 324 produces a volume of H2 gas that has approximately twice the volume of the generated O2 gas at equivalent pressure and temperature levels. In the hydrogen torch 104, the H2 storage tank 340 is either larger than the O2 storage tank 344, rated to store the H2 at a higher pressure level, or includes a combination of both a larger size and higher pressure rating to enable the H2 storage tank 340 to store approximately twice the number of H2 molecules compared to the number of O2 molecules that are stored in the O2 storage tank 344. In one embodiment of the printer 100, both of the tanks 340 and 344 are rated to store compressed hydrogen or oxygen at a pressure level of 20 pounds per square inch (PSI).
The hydrogen torch 104 of
In the hydrogen torch 104, the tanks 340 and 344 include outlet openings that are connected to inlets of the flow control valve 348. The flow control valve 348 is a variable valve that can control a rate of flow of the hydrogen and oxygen fuel from the tanks 332 and 336 to the nozzle 106. An external controller, such as the controller 128 in the printer 100, is operatively connected to the flow control valve 348. While the hydrogen torch 104 depicted in
During operation, the controller operates the flow control valve to control the rate of flow of fuel through the valve 348 to the burner nozzle 106, which changes the thermal output level of the flame through the nozzle 106 during operation of the hydrogen torch 104. In the configuration of
In the hydrogen torch 104, the nozzle 106 receives the fuel including the mixture of H2 and O2 gas from the flow control valve 348. The nozzle 106 directs the fuel to an outlet where the fuel ignites to produce a torch flame that is applied to the print surface of an object in the printer 100. To activate the hydrogen torch 104, an external control device, such as the controller 128 in the printer 100, generates an electrical signal that operates a piezoelectric spark device 352 to ignite the fuel that is emitted from the nozzle 106. The piezoelectric spark device 352 is activated to ignite the hydrogen torch 104 and, if necessary, to reignite the hydrogen torch 104 if the flame from the nozzle 106 is inadvertently extinguished during operation.
In the hydrogen torch 104, the electrolytic cell 324 generates hydrogen and oxygen gas independently of the operation of the hydrogen torch 104 to generate a flame via the nozzle 106. For example, in one mode of operation the DC voltage source 328 operates the electrolytic cell 324 to generate hydrogen and oxygen gasses that are stored in the tanks 340 and 344, respectively, prior to activation of the hydrogen torch 104. This configuration of the hydrogen torch 104 enables the use of an electrolytic cell 324 to generate the hydrogen and oxygen fuel at a rate that is below the rate of fuel consumption for the hydrogen torch 104 during operation, since the tanks 340 and 344 store a supply of fuel. Consequently, the printer 100 can utilize a smaller array of electrolytic cells 324 than are otherwise required to generate the fuel at the full rate of consumption for the hydrogen torch 104.
In one practical embodiment of the inkjet printer 100, the hydrogen torch 104 activates to produce a flame during approximately 25% of the time that the printer 100 is activated, while the printer 100 performs other operations such as inkjet printing or curing of printed images during which the hydrogen torch 104 is deactivated and does not produce a flame during the remaining 75% of the operational time in the printer. In this embodiment, the electrolytic cells generate a total volume of the hydrogen and oxygen fuel at a rate of approximately 18 liters per hour at standard temperature and pressure (STP), although different printer embodiments include electrolytic cells that produce the hydrogen and oxygen fuel at lower or higher rates. In the printer 100, the electrolytic cells 324 may be activated to generate the hydrogen and oxygen fuel while the hydrogen torch 104 is deactivated or during periods when the hydrogen torch 104 is both deactivated and activated to maintain a supply of fuel.
Referring again to
Referring to
In some configurations, the controller 128 identifies an estimated amount of fuel needed to apply the flame treatment to the print surface of the object 160 based on the two-dimensional area data or three-dimensional profile data 140 that are stored in the memory 132. The controller 128 operates the electrolytic cell 324 in the hydrogen torch 104 to generate a supply of hydrogen and oxygen fuel prior to commencing the flame treatment operation to ensure that the hydrogen torch 104 has a sufficient supply of fuel to complete the flame treatment operation without interruption.
In some embodiments, the controller 128 receives a stock keeping unit (SKU) number or other input identifier for an object via the user interface device 150. The user interface device 150 is, for example, push-button, keypad, or touchscreen interface that enables an operator to control the printer 100 and, in at least one operating mode, receive the SKU from the operator. In another configuration, the user interface device 150 is a network interface device such as a wired or wireless network adapter that enables the printer to receive the SKU and other control information from a remote computing system. The controller 128 identifies the two-dimensional surface area or three-dimensional profile data for the print surface of the object 160 using the input identifier and a database that contains the stored two-dimensional area and three-dimensional profile data 140. In one embodiment, the controller 128 retrieves the predetermined area and three-dimensional profile data from an external database (e.g. a web server or other network-connected database) using the SKU number or other identifier as a search key. In another configuration, the controller 128 generates an estimate of the surface area or three-dimensional profile of the object 160 using the displacement sensor 108 to perform multiple passes over the object 160 while the hydrogen torch 104 is deactivated. The controller 128 then stores the estimated area or three-dimensional profile information 140 in the memory 132 for subsequent flame treatment and printing operations on additional copies of the same object.
During the process 200, the printer 100 optionally identifies either or both of the two-dimensional surface area and the three-dimensional profile of the print surface prior to commencing the flame treatment (block 204). As described above, in some embodiments the controller 128 identifies the two-dimensional surface area or the three-dimensional profile data from the database of the surface area and profile data 140 that are stored in the memory 132 using, for example, the SKU number or other identifier that is received from the user interface device 150. In another embodiment, the controller 128 operates the displacement sensor 108 and one or both of the actuators 124A/124B to scan the print surface by performing one or more passes over the print surface, such as the surface of the object 160 in
The process 200 continues as the controller 128 optionally generates an estimate of the amount of fuel that is required to apply the flame treatment to the print surface and activates the electrolytic cell to produce fuel, if necessary, based on the estimate (block 208). As described above, the controller 128 generates the estimate of the required fuel consumption to apply flame treatment to the print surface based on either the two-dimensional surface area or the three-dimensional profile data for the print surface. The controller 128 also uses predetermined characteristics of the hydrogen torch 104 to generate the estimate. The predetermined characteristics include, for example, predetermined fuel flow rates for different thermal output levels of the hydrogen torch 104, the velocity of movement for the torch nozzle 106 during each pass over the print surface of the object 160, the surface area that receives the flame treatment from the torch nozzle 106 during each pass, and the corresponding number of passes that are required to cover the entire area of the print surface. The controller 128 identifies the available fuel level in the hydrogen torch 104 based on pressure levels in the hydrogen tank 340 and the oxygen tank 344. The controller 128 activates the DC electrical power source 328 to generate additional hydrogen and oxygen with the electrolytic cell 324 as needed until the hydrogen torch 104 has a sufficient supply of fuel available to perform the flame treatment process based on the estimated fuel consumption requirement.
The process 200 continues as the controller 128 activates the hydrogen torch 104 to generate the flame for flame treatment (block 212). In the embodiment of
As the torch nozzle 106 moves relative to the print surface of the object 160, the displacement sensor 108 generates measurement data that indicates the distance between the nozzle 106 and the print surface over different portions of the print surface, such as the portions 162 and 164 that are depicted in
In the example of
During the process 200, the printer 100 operates one or both of the actuators 124A/124B to perform multiple passes between the torch nozzle 106 and the print surface on the object 160 to enable the torch nozzle 106 to apply the flame treatment to the entire print surface prior to a printing operation in the printer 100.
After the completion of the flame treatment process, the controller 128 deactivates the hydrogen torch 104 (block 224) and operates one or more inkjet printheads in the printer to form a printed image on the flame treated print surface (block 228). In the printer 100, the controller 128 closes the flow control valve 348 to deactivate the hydrogen torch 104. As described above, in some configurations the controller 128 activates the DC electrical source 328 to generate additional fuel using the electrolytic cell 324 while the hydrogen torch 104 is deactivated to produce a supply of hydrogen and oxygen gas fuel for a subsequent flame treatment process. In the printer 100, the controller 128 operates the actuators 124A/124B to perform one or more passes between the printhead 120 and the flame treated print surface on the object 160. The controller 128 uses the stored image data 144 to form printed patterns including text, graphics, and optionally protective coatings on the print surface of the object 160. In the illustrative embodiment of
It will be appreciated that variants of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems, applications or methods. Various presently unforeseen or unanticipated alternatives, modifications, variations or improvements may be subsequently made by those skilled in the art that are also intended to be encompassed by the following claims.
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