The present invention relates generally to ink management systems for printing presses, and more specifically to automatic ink cartridge dispensers for dispensing ink into the fountains of offset printing presses.
Briefly described, one embodiment of the present disclosure comprises a method of dispensing ink that includes installing a cartridge having a ink-filled chamber into an ink dispenser of a printing press, in which the chamber of the cartridge is defined by a tubular body, a fitment at a dispensing end having one or more outlet ports closed by a valve, and a plunger that is slidably disposed in a open end of the tubular body opposite the dispensing end. The cartridge is then weighed in situ with a weighing device that is positioned within the ink dispenser to determine an initial weight of the cartridge, prior to dispensing ink from the cartridge. The method further includes dispensing ink from the cartridge during a print job until the print job is complete or until the cartridge is substantially empty, and then again weighing the cartridge in situ with the weighing device to determine an ending weight of the cartridge prior to removing the cartridge. The method further includes subtracting the ending weight from the initial weight to determine the weight of the ink dispensed into the printing press during the print job.
In accordance with another embodiment, a system for dispensing ink into the fountain of a printing press that includes one or more ink cartridges, with each ink cartridge having a ink chamber defined by a tubular body, a fitment at a dispensing end having one or more outlet ports closed by valve, and a plunger that is slidably disposed in an open end of the tubular body opposite the dispensing end. The system further includes an ink dispenser positioned above the fountain of the printing press and having a receptacle that is adapted for removably receiving one of the ink cartridges. The receptacle of the ink dispenser further includes a weighing device at a lower end and a power cylinder that is mechanically coupled to a pusher plate at an upper end. The cartridge is received within the receptacle with the dispensing end supported on the weighing device for in situ weighing of the cartridge and any ink contained therein, and with the pusher plate becoming engaged with the plunger through the open end of the cartridge.
The invention will be better understood upon review of the detailed description set forth below taken in conjunction with the accompanying drawing figures, which are briefly described as follows.
Those skilled in the art will appreciate and understand that, according to common practice, various features of the drawings discussed below are not necessarily drawn to scale, and that dimensions of various features and elements of the drawings may be expanded or reduced to more clearly illustrate the embodiments of the present invention described herein.
The present disclosure relates to a system and one or more methods for dispensing ink into a printing press, and particularly into the fountain of a web-fed or a sheet-fed offset printing press. The system and methods generally include means for in situ determination of the weight of ink dispensed into the fountain during the print job. As described in more detail below, the ink dispensing system and methods disclosed herein can provide several significant advantages and benefits over other types of ink dispensers or methods for providing ink to a printing device. However, the recited advantages are not meant to be limiting in any way, as one skilled in the art will appreciate that other advantages may also be realized upon practicing the present disclosure.
Referring now in more detail to the drawing figures, wherein like features are identified with like reference numerals throughout the several views,
The ink dispensing system 20 includes an ink dispenser 40 that is configured to removably receive a cartridge 80 containing the ink 25. As shown in
The ink dispensing system 20 also includes a powering apparatus 50 for driving the dispensing of ink 25 from the cartridge 80. As shown
The ink 25 within the fountain 14 commonly is viscous such that the level of the ink 25 in the fountain becomes drawn down locally at various places across the width of the fountain and the fountain roller 16, in accordance with the differing ink demands of the pattern being transferred to the printable media. To better distribute the ink 25 to the locations that need it most, in some aspects the ink dispensing system 20 can further include one or more sensors (not shown) for sensing and monitoring the level of ink 25 across the width of the fountain 14, and which are in electrical communication with the electronic control device 70 that is configured to activated the ink dispensing 40 when it is positioned over a low spot. As the control device 70 for operating the positioning system 30, for monitoring the level of the ink 25 in the fountain 14, and for activating the ink dispenser 40 at the appropriate time is generally known in the art, it will not be discussed further except for how it may be integrated or combined with the improved system and method for dispensing ink that is disclosed herein.
As shown in
The dispensing fitment 86 includes one or more outlet ports 87 closed a valve 88, such as a spring-loaded one-way valve. The outlet port 87/valve 88 can be centered within the fitment 86 and configured to automatically open in response to an increase in the pressure within the cartridge 80 above a predetermined threshold. In one aspect the profiles of the interior surfaces of the plunger 82 and the dispensing fitment 86 can be matched to minimize any empty space between the two surfaces once the plunger has been pushed all the way down to the dispensing end 87, so as to minimize any residual amount of ink that remains within the cartridge 80 after its removal from the ink dispenser 40.
Once a cartridge 80 has been installed within the receptacle 41, the load cell 46 can be used to measure its weight in situ at various times during one or more printing cycles or print jobs, including but not limited to (a) before the beginning of ink dispensing and (b) after the completion of ink dispensing, such as when the cartridge is emptied of ink or the print job is completed. In this manner the total weight of the ink, or ink weight, dispensed into the fountain during the printing cycle or print job can be directly and accurately determined while the cartridge remains installed into the receptacle 41. In turn, the ink weight can be applied by the operator of the printing press or the supplier of the ink to accurately quantify the cost of the ink that was used in a particular printing cycle or print job.
The ability to determine the ink weight accurately and directly while the cartridge 80 is installed within the ink dispenser 40 can be a significant advantage over existing methods for determining the cost of the ink dispensed during a printing cycle or a print job. For instance, existing methods for determining ink weight generally rely on a calculation that is based on the volume of the dispensed ink and its specific gravity. However, the specific gravity of inks can vary widely depending on their type, color, manufacturer, and the like, while a precise value for the volume of the ink dispensed into the fountain using existing pneumatic-drive ink dispensers is also difficult to determine. Thus, using existing volume-based technologies and methods to obtain an accurate value for the ink weight at each printing press station, especially during a print job that applies multiple colors to the printed media, can be problematic.
Directly measuring the weight of the dispensed ink in situ, or while the cartridge 80 is installed within the receptacle 41 of the ink dispenser 40, can be especially useful in print jobs that dispense only a partial amount of the ink from the cartridge 80 during a print job, such that a portion of usable ink remains in the cartridge after the print job is complete. If desired, this process can allow the user to leave the cartridge 80 within the ink dispenser 40 until the next print job is started, at which point the partially-filled cartridge is again weighed before the beginning of ink dispensing and after the completion of ink dispensing, and the value for the ink weight dispensed into the fountain for the new printing cycle can be applied to the new print job. Alternatively, the partially-filled cartridge can be removed for storage and/or later use on a subsequent print job that calls for the same ink, with the initial amount of ink weight being easily determined without regard to the specific gravity of the ink or the size of the cartridge. The ink dispensing system 20 and its method of use can thus facilitate the usage of partially-filed and/or previously-used ink cartridges in a more efficient manner.
The powering system 50 for mechanically pushing or driving the slidable plunger located in the upper end of the upright cartridge 80 can be installed above the top plate 45 of the receptacle 41. In one aspect the powering system 50 can include a pneumatic power cylinder 52 supported above the receptacle 41 with a piston rod assembly extending downward through an aperture in the top plate 45. The piston rod assembly can comprise the piston 54 within the power cylinder 52, a piston rod 56, and a pusher plate 58 that is attached to the distal end 57 of the piston rod 56 and configured to engage with the outer surface of the plunger 82. In one aspect the pusher plate 58 can be removable or interchangeable with pusher plates having different sizes and/or shapes, so as to better connect with cartridges having plungers with different sizes and/or shapes.
As shown in
When the cartridge 80 is first installed into the receptacle 41 with the dispensing end 87 supported upon the adapter plate 44, the cartridge 80 can be held in a centered and upright position by one or more support brackets or fixtures (not shown but known in the art). Once the cartridge 80 is supported within the receptacle 41, the load cell 46 can be activated or queried to measure an initial weight of the cartridge 80 and to provide that signal or data (depending on the type of electronics included within the circuitry of the load cell 46) to the electronic control device 70 via communications cable 47. It is understood that the initial weight measured by the load cell 46 generally comprises the weight of both the empty cartridge 80 and the ink 25 contained therein.
Once the initial weight of the cartridge 80 has been determined, the pneumatic circuit 60 can be activated to direct compressed air into the forward end 53 of the power cylinder 52, thereby pushing the piston rod 56 downward until the pusher plate 58 engages with the plunger 82. In one aspect the powering system may be configured so that that pusher plate 58 only lightly engages the plunger 82 on its initial contact, and without sufficient force to increase the pressure within the ink chamber above the pressure threshold that would cause the valve 88 in the outlet port 87 of the dispensing fitment 86 to open. The quick release valve 68 in the pneumatic circuit 60 can then be opened to release the compressed air within the forward end 53 of the power cylinder 52, leaving only the empty weight of the piston rod assembly pressing down on the plunger 82. Alternatively, the pressure regulator 64 can be operated to open the valve assembly 66 and simultaneously release the pressure within both the forward end 53 and the return end 55 of the pneumatic power cylinder 52, so as to allow the piston rod assembly to drop down under its own weight to engage the plunger 80.
At this point the load cell 46 may be activated or queried again to take a combined weight measurement of the cartridge weight, ink weight, and dead weight of the piston rod assembly. If the weight of the empty cartridge is known, and if the dead weight of the piston rod assembly is also known or can be determined by subtracting the initial weight from the first combined weight measurement, subsequent combined weight measurements can then be used to estimate and/or monitor the amount of ink remaining within the ink cavity 81 of the cartridge 80 throughout the printing cycle. Generally, in this step either the quick release valve 68 and/or the valve assembly 66 would be opened to ambience to release any compressed air with the power cylinder 52 prior to the measurement that would affect is accuracy in either the heavier or the lighter directions.
To dispense ink from the cartridge 80, such as when a sensor detects a localized low spot in the level of ink 25 with the fountain 14 (
The ink in the cartridge 80 will generally be dispensed at intermittent intervals during the print job or printing cycle, as indicated by the ink level sensor and monitored by the electronic control device 70. When the powering system 50 is activated to apply pressure to the plunger 82, the increase in pressure within the ink cavity 81 can be sensed as increased weight by the load cell 46. If the ink 25 has the characteristics of an incompressible fluid, the pressure (or weight) will rise near instantaneously until it reaches the release pressure for the spring-loaded valve 88 that opens to allow ink to flow through the outlet port 87 into the fountain of the printing press station.
After the opening of the valve 88, the continued pressure applied by the powering system 50 can further affect the rate at which ink is dispensed. For example, if the ink cavity pressure is maintained near the release pressure of the valve 88, the ink can be dispensed at a low or moderate flow rate as determined by the size of the outlet port aperture. If the ink cavity pressure rises substantially above the release pressure of the valve, however, the ink can be dispensed at a much faster rate. In one aspect of the disclosure, the output of the load cell can monitored throughout the dispensing cycle as an indirect measurement of the dispensing rate and/or amount of ink that is dispensed into the fountain. If desired, the output of the load cell can further be applied in a control loop that feeds back to the powering system 50 to adjust the pressure applied by the power cylinder 52, with the pressure being continuously adjusted to control the flow of ink from the cartridge.
When the desired amount of ink has been deposited into the fountain, the powering system 50 can be deactivated and the pressure within the ink cavity 81 allowed to drop back below the release pressure of the valve 88, which automatically closes to stop the flow of ink. In one aspect of the ink dispensing system, the quick release valve 68 can again be opened to release the compressed air within the forward end 53 of the power cylinder 52, and another intermediate combined weight measurement of the cartridge weight, ink weight, and dead weight of the piston rod assembly can again be captured to estimate the amount of ink remaining within the cartridge 80. If desired, the electronic control device 70 may be programmed to compare the difference between combined weight measurements before and after a dispensing cycle against the indirect measurement of the dispensing rate during the dispensing cycle to ensure that the dispensing system is operating accurately.
Accordingly, the weight or amount of the ink in the ink cavity can be continuously monitored throughout the printing cycle using one or more of the methods described above. As the container approaches an empty condition, the electronic control device 70 can be programmed to notify the operator of the printing press of the anticipated depletion of the cartridge, and provide the operator with one or more options. For example, if the operator determines that the print job is nearly complete and the ink currently deposited within the fountain is sufficient to finish the printing cycle, the operator may choose to disable the ink dispensing system 20 from dispensing any more ink for the remainder of the print job. Alternatively, if the operator determines that remaining ink in the cartridge together with the ink currently deposited within the fountain will be sufficient to complete the print job, the operator can elect to let the normal printing cycle continue through to completion with the installed printing cartridge. In yet another embodiment the operator may determine that the remaining ink in the cartridge together with the ink currently deposited within the fountain will be insufficient to complete the print job, in which case the operator can activate the electronic control device 70 to manually dispense the remaining ink in the cartridge prior to its normal emptying time, thereby giving the operator additional time to remove and replace the used cartridge with another cartridge, whether new or previously used, having sufficient ink contained therein to complete or extend the printing cycle until the print job is complete.
After completion of the dispensing, such as when the cartridge is emptied of ink or the print job is completed, the valve assembly 66 in the pneumatic circuit 60 can be controlled by the pressure regulator 64 to release the pressure within the forward end 53 of the pneumatic power cylinder 52 and to direct compressed air into the return end 55, thereby raising the piston rod assembly back to its initial position and withdrawing pusher plate 58 from the tubular body 84 of the cartridge 80. The load cell 46 can be then activated or queried to measure the ending weight of the cartridge 80 prior to its removal from the receptacle 41 of the ink dispenser 40. Whether the cartridge 80 is empty or still partially filled with ink, the electronic control device 70 can be programmed to subtract the in-situ measurements of the ending weight of the cartridge 80 from its initial weight to accurately and directly determine the weight of the ink that was dispensed into the fountain 24 of the printing press unit 22 during a printing cycle. Furthermore, if multiple cartridges and printing cycles are used during a particular print job, the electronic control device 70 can be programed to track and combine the weight of the ink dispensed from each cartridge to determine the total dispensed ink weight.
With reference back to
The ink dispensing system and methods of the present disclosure been described herein in terms of preferred embodiments and methodologies considered by the inventor to represent the best mode of carrying out the invention. It will be understood by the skilled artisan, however, that a wide range of additions, deletions, and modifications, both subtle and gross, may be made to the illustrated and exemplary embodiments of the composite sheet without departing from the spirit and scope of the invention. For example, the powering system can be activated to lift the piston rod assembly off the top face of the plunger prior to intermediate measurements of the cartridge and ink weight during a printing cycle, or the pneumatic system can be replaced with an electrical system which utilizes linear motors or servo-motors and a drive rod or drive screw to engage the pusher plate with the top face of the plunger. These and other revisions might be made by those of skill in the art without departing from the spirit and scope of the invention that is constrained only by the following claims.