Patent Publication Number: US-7916355-B2

Title: Combined flexographic and intaglio printing press and operating system therefor

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of and claims the benefit of U.S. patent application Ser. No. 10/508,849, filed Sep. 24, 2004, which was a national stage entry of PCT Application No. PCT/US03/09267, filed Mar. 27, 2003, which claimed priority to U.S. Provisional Application No. 60/367,906, filed Mar. 27, 2002. The disclosures of each prior application are incorporated by reference herein in their entireties. 
    
    
     DISCLOSURE OF THE INVENTION 
     The invention encompasses the combination of two printing technologies into a single web fed printing press  10 , particularly the combination of flexographic  14  and intaglio  17  printing. Other features may be present in the combination web printing press  10  as well, such as die cutting, offset printing, gravure printing, hologram application, and the like. The aforementioned combining process is accomplished through the use of precision servo motors  35  coupled with motion control hardware  40  and software (Appendix). The computer programs (Appendix) incorporated into this application were written by the inventor to accomplish the complex process of marrying two dissimilar printing processes in a single press. 
     The combination of two dissimilar printing processes is a complex problem of motion control. Web tension and position must be maintained throughout the printing process in order to achieve accurate print registration. The inventor has implemented precision control of the web using high accuracy servo motors  35  combined with low inertia drive rollers  25 ,  39 ,  42 . A multi-processor motion control system  40  commands the activity of the servo motors  35  and monitors the resultant movement with digital position feedback. All solenoids, lights, and switches are interfaced to the press computer  40  using an integrated programmable logic controller. 
     The press controller  40  is comprised of a PC based computer using RISC based motion control boards. Each RISC based motion control board has its own processor, and supports up to eight channels of motion control. A single servo motor  35  defines a channel. Each point of web control uses a unique servo motor  35 . Each motion control board runs a unique software program created by the inventor. The operator interface is driven by the host PC running Microsoft Windows and an application program (Appendix). This application program obtains information from the operator, converts it to machine commands, and passes it to the motion control boards via the PC back plane. It is the host PC application that coordinates the entire operation of the press  10 , including programmable logic controller functions. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1A  is a diagrammatic side elevational view of flexographic and intaglio print units according to the present invention; and 
         FIG. 1B  is a diagrammatic side elevational view of optional finishing or processing units disposed downstream of the components shown in  FIG. 1A . 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     As illustrated in  FIGS. 1A and 1B , the present combination flexographic and intaglio printing press, generally designated  10 , can be looked at as a multi-axis robot. Robots are thought to handle materials in an orderly way, moving them from one place to another, and performing operations along the way to alter the effect of the material. The press handles substrate or web material  11  wound in a roll  12 , typically on a three inch cardboard core with an outside diameter of forty inches. The number of feet of material  11  on the roll depends on the type and thickness of the material being printed. The press is not limited to printing on paper; films, polymers, and the like are also suitable as a printing substrate  11 . The width of the substrate or web  11  is a function of the design width of the combination press. An unwinder  13  acts as a delivery device for the substrate  11 . The substrate  11  is pulled from the unwinder  13  by a first flexographic print unit  14  in the press line. The unwinder  13  includes a conventional tensioning mechanism  16  to provide resistance. The degree of resistance applied to the web by the unwinder  13  is adjustable, and regulated by a stand-alone tension controller. 
     All of the printers in the press line are flexographic print units  14 . Preferably, the flexographic press units  14  precede the intaglio print units  17 . One or more flexographic print units  14  apply ink to the substrate  11 . The units&#39; motion can be effected as a group with a single servo  35 , or independently with a servo  35  for each print unit  14 . The servo(s)  35  are controlled by a motion controller board  45  in the press computer  40 . Since axis or unit numbers are generally assigned chronologically from the first unit in the line up, the first flexo  14 , or group of flexo units  14  are assigned unit  1 . This or these servos receive speed and position information from the motion controller  45 . A reference signal to the motion controller(s) is derived from one of two sources: 1) in Flexo only mode, where the press is printing with the Intaglio unit disabled, the reference signal is synthesized from internal reference generator software, and 2) in combination mode, the reference signal is generated by an optical encoder  21  mounted on the intaglio unit drive  22 . The motion controller  45  generates a command to the servo based on the reference signal generated and other parametric data such as operator data, print repeat length, and so on. Print registration (the alignment of one printed feature to another) can be adjusted by actions of the operator making entries to the host computer, which is translated to machine commands, and ultimately affects the command to the servo(s). The printed ink is dried at each flexographic print unit  14 , typically with hot air or ultraviolet light. Operator pushbuttons at the unit(s)  14  connect to the integrated PLC. Each action at one or more of the pushbuttons is evaluated by the integrated PLC in the host computer  40  which gets translated to machine commands, resulting in appropriate action by the motion controller(s)  44 ,  45 . 
     The intaglio unit  17  generally follows the flexographic print unit(s)  14 . The press will include one or more intaglio print units  17  and contain one or more inking units  23  each. Intaglio units  17  also include some form of wiping system  24  to remove excess ink applied to the plate. The intaglio unit(s) may also contain a prewipe system that removes excess ink from the plate. Each of the subsystems within the Intaglio unit(s) is controlled by the integrated PLC. Multiple servos coordinate the movement of paper through each intaglio unit. 
     When the press operator selects the operating mode of flexographic only, which may include other units on the press such as the aforementioned ones, the intaglio unit(s)  17  is inactive. The operator bypasses the intaglio unit(s)  17  by creating a web path around the unit(s). This is accomplished by passing the web  11  over rollers that route the web over or under said unit(s). Press motion commands from pushbuttons such as Jog and Run cause no movement within the Intaglio unit(s). Servo motor speed and position information is created using an internal synthesized method. 
     When combination print mode is selected, the first intaglio unit  17  in the press line generates the motion reference signal. All servo movement is coordinated by this signal. Flexographic unit(s)&#39; servo(s) move in conjunction to the reference signal. The signal is conditioned by parametric data such as print repeat length, web tension set point, and the likes. Software algorithms continuously compute the associated servo commands which, when combined with servo motor digital position feedback, provide precise movement of the servo. It is said that this activity is referred to as an electronic gearbox. The software controls which signals and parameters are needed to effectively maintain registration between each dissimilar unit(s) in the press line. Complex algorithms message the reference signal before passing it on to the specific servo motors. The intaglio unit(s) utilize a “stop-n-go” substrate transport. This mechanism creates an intermittent movement of the web similar to a movie projector. A series of four servos establish the intermittent motion. Since the Flexographic and other units in the press line require continuous and stable web movement, it is necessary for the “stop-n-go” transport to accept web as continuous flow and deliver web in a continuous flow to the next unit in the line. Each servo drives a pull roller  25  that the web contacts, thus allowing the servo to affect the position of the web. The implementation of the servos is as follows: 1) the first servo pulls web in a continuous manner from the previous unit. Its motion command from the motion controller is based on the reference signal and the parameters associated with web tension settings. It pushes the web into a vacuum box  26 , which is used as an accumulator. A vacuum pump insures that adequate vacuum is present to receive web at the speed necessary. 2) The second servo, referred to as shuttle drive # 1 , pulls web from vacuum box # 1  and passes it to the intaglio plate cylinder  27 . The command for this servo is based on the reference signal and several other key elements. It is the responsibility of this servo to position the web in register with the image on the intaglio plate. The intaglio plate is mounted to a cylinder that has a circumference of double the largest Flexo plate cylinder. The intaglio plate cylinder is moving at twice the surface speed as the Flexo plate cylinder(s) so that both make a revolution in the same period of time. The shuttle # 1  servo creates an intermittent motion pattern of web so that part of the time the web is stopped while part of the time the web is moving twice the speed as is the other units in the press line. The algorithm that generates the command to the servo uses the reference position to calculate the position of the shuttle 500 times per second. A mark sensor reads registration marks printed by the first unit in the press line to adjust the motion commands to permit perfect registration. It is the register mark that allows the motion controller to compensate for slippages in the web across rollers, slight elongations in the web, and other artifacts of the printing process. The motion algorithm uses a sine type pattern generator thereby creating a smooth transition from the “web stopped” portion of the cycle to “web moving” portion of the cycle. This sinusoidal pattern of motion is synchronized to the leading edge of the intaglio printing plate by the reference, and its relationship to the registration marks read on the web. Mark register data is collected through direct connection of the mark sensor to the motion controller board(s). 3) The third servo is referred to as shuttle servo # 2 . This servo accepts web from shuttle servo # 1  after printed by the intaglio plate cylinder. The servo&#39;s command is identical to that of shuttle servo # 1  with one exception: this servo command includes additional parametric data to create a slight difference in position relative to shuttle servo # 1 . In numerical terms, when shuttle servo # 1  moves 1″ forward, shuttle servo # 2  may move 1.001″ forward. This creates a slightly higher web tension while the web undergoes intaglio printing. Parametric data affects the amount of gain in shuttle servo # 2 . Shuttle servo # 2  passes the web to vacuum box # 2  ( 28 ), which serves as an accumulator as does vacuum box # 1 . 4) The fourth servo in the transport pulls web from vacuum box # 2  and passes it to the next unit in the press line. This servo is running in a continuous motion mode, based on the reference signal. Parametric data establishes the electronic gear ratio so that the web is being delivered to the next unit at the same position and speed as the first servo accepted web from the previous unit on the press line. 
     Once the web  11  is printed with the intaglio ink, it passes through a forced air dryer  18 . A chill unit  19  follows next in the press line, cooling the back to ambient temperature from a highly elevated temperature in the intaglio dryer  38 . The web is passed across several chilled rollers  30  in a zigzag pattern. Circulating refrigerated water through the cores chills the rollers. The chilled rollers  30  are driven by a servo motor  35  that receives its command based on the reference and parametric data such as web tension settings. Additional intaglio unit(s)  17  would follow the first intaglio unit, if included. Their operation is identical to that of the first intaglio unit, described above. 
     As illustrated in  FIG. 1B , finishing or processing units follow in the press line. These units may consist of one or more of the following: die cutting unit  33 , registered holographic application unit RFID applicator, numbering, or other. Each respective unit would be driven by a separate servo motor  35 , which receives its command from the motion controller board(s). These units and their respective servo move the web in a continuous motion, using parametric data to affect registration and tension. Each unit may include a mark sensor to further affect the motion command. Precise registration is obtained when mark sensor data is part of the motion command, as web distortion, elongation, and the likes, become known in the calculations for the command. Likewise, conventional rewinding  37 , folding, and/or sheeting apparatus may be included in the press line. Once the web is printed, and other features are added as necessary, the web gets delivered as follows depending on customer requirements: A rewinder  37  accepts web from the previous unit in the press line and winds it onto paper cores. The size of the core and the overall dimension of the finished roll are dependent on the type of rewinder used and customer requirements. Typically, a roll would be wound on a 3 inch core and a 40 inch finish diameter. Rewinders are generally stand-alone units that receive basic run/stop information from the integrated PLC. Folders are driven by a servo motor that receives commands based on the reference and parametric data. A folder delivers the web in a fan folded format, and subsequently gets boxed in 2500 folded documents to a box. A sheeter is driven by a servo motor that receives commands from the motion controller(s) based on the reference signal and parametric data. A mark sensor normally accompanies the controls for a sheeter, as the cut position is a close registration feature. A sheeter accepts web from the previous unit in the press line and cuts the web into a equal length documents that are subsequently boxed by the 500 to 2500 unit count. The cut registration is accurately maintained when a mark sensor is incorporated to read the registration mark printed by the first active unit in the press line. 
     Software algorithms utilize digital data from devices on each of the units on the press line, incorporate that information with parametric data from the operator, and configuration data that specifies the resolution of each position encoder, the circumference of cylinders and pull rolls, and other machine specific data. It is this data that results in precise commands to each servo in the press that in turn results in accurate movement of the web under all operating conditions. Preferably, each servo has a separate algorithm evaluating the data and issuing commands. Electronic gearing can be thought of as the general activity of each algorithm. Additional computations take dynamics into account that include web stretch, web elongation, and other web distortions. In the case of the intaglio unit(s)  17 , the shuttle roller  39  movement is based on a profile, or cam pattern. It&#39;s commanded position is continuously modified by position mark sensor data. The press operator adjusts parameters on the graphics display that results in web tension changes, as required by various substrate types. Algorithms adjust the servos commands so that the respective servo runs slightly slower or faster than the previous unit. 
     GLOSSARY 
     Prewipe unit: Used in conjunction with intaglio printing. An inking unit applies ink to the intaglio printing plate. The prewipe unit contacts the plate next for the purpose of removing excess ink from the printing plate. A typical configuration of a prewipe unit would include the prewipe roller, a doctor roller, and a doctor blade. The doctor roller removes the ink from the prewipe roller, and the doctor blade removes ink from the doctor roller. The removed ink is collected in a recovery system for either disposal or recycling. 
     Reference: This is the signal that orchestrates the movement of servos in the press line. It can be thought of in the same way as a conductor in an orchestra. 
     Registration: The alignment of multiple features to a substrate. An example is the alignment of two separate colors on a web. Another would be the alignment of printing on the web to that of a die cutting unit. 
     Servo motor: Refers to a high precision variable speed motor. Servos possess the ability to maintain precise speeds, accelerate or decelerate loads in a fraction of a second. Web: The stream of paper or other substrate that spans the length of the press is the web. It starts at the unwinder, pulled from a roll, and extends to the delivery end of the press where it is either rewound into a roll, cut into sheets, or folded. 
     Wiping System: Part of an Intaglio print unit, the unit removes excess ink from the engraved printing plate. An intaglio inker applies ink to areas of a printing plate. The wiping system removes all ink from the surface of the plate thus leaving in only the engravings on a plate. When a prewipe system is included, it tends to reduce the load on the wiping system by taking a preliminary wipe on the plate. Wiping systems come in two forms, and are vastly different from each other. They are: 1) Water wipe system. A water wipe system utilizes a rubber covered roller that contacts the printing plate, rotating so that its surface is moving in the opposite direction as the plate cylinder. This effectively rubs the ink off the surface of the printing plate. Once the ink is collected on the wiping cylinder, it later comes in contact with cleaning solution, brushes, and a doctor blade. The process of wiping and cleaning is ongoing. The cleaning solution carries the excess ink away which is disposed in a separate process. 2) A paper wipe system removes ink similarly to the extent that the wiping roller is used to press paper against the plate, using the same opposite direction movement. In this system, the ink is carried away on the paper, which starts at an unwinder, runs across the wiping roller, then rewound onto a paper core. 
     The press  10  utilizes three separate software programs (Appendix), each running on it&#39;s own processor  40 ,  44 ,  45 . An industrial PC  40  runs the host software with two RISC processor based motion control boards  44 ,  45  plugged into the industrial PC back plane. The industrial PC  40  acts as the host to coordinate the activities of itself and the motion control processors  44 ,  45 . Operator interaction takes place through the host processor through the use of color graphic screen information and input through a keyboard/mouse combination or a touch screen. The motion control processors  44 ,  45  interpret commands from the host  40  via the PC back plane and carry out the activity of managing the machine motion throughout the press  10 . 
     The first motion control processor  44  manages the activities of the intaglio unit  17  including the stop and go web transport. It also generates timing signals that one or more other motion control processors  45  utilize to synchronize web motion so as to maintain web tension and registration. 
     When the press  10  is operated in the combination mode where the intaglio printing is taking place in conjunction with the flexo printing and possibly other features on the press, the following process is utilized to manage motion: 1) The operator initiates a command to run the press via a run pushbutton; 2) the run command is interpreted by the host  40 , and subsequently passes the command on to the first motion processor  44 ; 3) the first motion processor  44  enables the main drive  22  on the intaglio unit  17  and sends it a speed command; 4) the intaglio gear train, coupled with the main printing cylinder  27 , rotates at the preset speed, which in turn causes the mechanically coupled reference encoder  21  to rotate; 5) the signal from the reference encoder is fed to the first motion processor  44 ; 6) the value of the reference encoder provides a binary number that points to a lookup table in the processor  44  signifying the position of each of the servo motors used to position of the web  11 ; 7) the values in the lookup table are adjusted both statically when the press is calibrated and dynamically as a result of reading information about the web  11  on an ongoing basis via registration mark sensors and web tension sensors (the location of each of the sensors is dependant on the press configuration and may or may not exist depending on the press configuration); 8) the first motion processor  44  also distributes the value of the reference encoder in real time across the PC back plane to the other motion processor(s)  45 ; 9) the other motion processor(s)  45  adjust the position of their respective servo motors based on their respective lookup tables. 
     When the press is operated without the intaglio unit  17 , the first motion processor  44  generates a synthesized reference encoder signal that it uses and distributes to the other motion control board  45 . In this case, the sequence of activity matches that of the combination mode with the following exceptions: 1) the host run and speed command is converted to the synthesized signal rather than generating the enable and speed commands to the intaglio main drive.