Abstract:
A web fed rotary printing press apparatus and a method for operating the same which includes at least one reconfigurable printing mechanism, a sensor for detecting the end of a print job, and a controller coupled to the sensor and the at least one printing mechanism for providing control signals representing predetermined printing parameters for a subsequent print job to the at least one print mechanism upon detection of the end of a print job. The apparatus may further include a planning computer coupled to the controller for generating printing parameters for each print job based on user input. Furthermore, the printing parameters generated by the planning computer for a print job may be stored as data in JDF files communicated to the controller which may be used to provide control signals representing predetermined printing parameters for a print job based on the data in the JDF files.

Description:
[0001]    The present invention relates generally to web printing presses and more particularly to a system for providing web printing press management. 
       BACKGROUND 
       [0002]    In certain printing operations, a web is fed from a roll mounted in a splicer to a sequence of printing equipment, which may include a number of different print mechanisms such as an infeed unit, a plurality of printing units, a dryer, a cooling unit, a folder superstructure and a delivery unit. The output of the delivery unit may be a plurality of signatures, formed from folded ribbons, the web being slit into ribbons, each signature having a printed image. The individual signatures may be assembled with other printed signatures to form a final product, such as a newspaper. 
         [0003]    Some printing presses are manually reconfigured for different print jobs by way of discrete individual adjustments between different print jobs when the printing press is not in operation. This method of reconfiguration increases the risk of human error and contributes to inefficiency, considerable production down-time and waste of valuable run-time. 
       SUMMARY OF THE INVENTION 
       [0004]    It is an object of the invention to provide a printing press which is automatically reconfigured and thus overcomes the problems associated with manual reconfiguration. 
         [0005]    The present invention is addressed to a method for automatically controlling a printing press including at least one reconfigurable printing mechanism. At least one reconfigurable printing mechanism is configured to print according to a first set of predetermined printing parameters for a first print job and then the first print job is printed on a first print web. The completion of the first print job detected, at least one reconfigurable printing mechanism is automatically configured to print according to a second set of predetermined printing parameters different from the first set of predetermined printing parameters for a second print job, and the second print job is printed on a second print web. The first print web may be the same size as the second print web, or the first print web may a different size as the second print web. 
         [0006]    The present invention is also addressed to a web fed rotary printing press apparatus which comprises at least one printing mechanism which is reconfigurable based on received control signals, a sensor for detecting the end of a print job, and a controller coupled to the sensor and at least one printing mechanism and which provides control signals representing predetermined printing parameters for a subsequent print job to the at least one print mechanism upon detection of the end of a print job. The apparatus may further include a planning computer coupled to the controller for generating printing parameters for each print job based on user input. Furthermore, the printing parameters generated by the planning computer for a print job may be stored as data in JDF files communicated to the controller which may be used to provide control signals representing predetermined printing parameters for a print job based on the data in the JDF files. 
         [0007]    In an alternative embodiment, the planning computer functions are included in the controller which also generates printing parameters for each print job based on user input. In this alternative embodiment, the printing parameters generated by the controller may also be stored as data in JDF files and the control signals provided by the controller representing predetermined printing parameters for a print job may be based on the data in the JDF files. 
         [0008]    In an embodiment of the invention, at least one of the printing mechanisms is a slitter which can be automatically reconfigured to slit the web at different positions, and the slitter is automatically configured by laterally moving at least one slitter blade in the slitter. Separate actuators may be provided which are associated with each slitter blade for moving the slitter blades laterally. Sensors may be provided which detect the completion of the first print job by sensing predetermined register marks on the first print web or by the job count, for example, good product delivered. The slitter may be moved to a new slit position with the web in motion. The ribbon path to the former would have to remain the same. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The above and related objects, features and advantages of the present invention will be more fully understood by reference to the following detailed description of the presently preferred, albeit illustrative, embodiments of the present invention when taken in conjunction with the accompanying drawings wherein: 
           [0010]      FIG. 1  schematically shows an exemplary embodiment of a printing press which can be automatically reconfigured from a current print job to a next print job; 
           [0011]      FIG. 2  schematically shows an example of an automatic slitter adjustment for a print job transfer from a wider web to a narrower web; and 
           [0012]      FIG. 3  schematically shows an example of an automatic slitter adjustment for a print job transfer from a narrower web to a wider web. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0013]    The Job Definition Format (JDF) is an industry specification for exchanging product specifications using an Extensible Markup Language (XML)-based file format. JDF files are often used in the printing industry to simplify data exchange between different applications and systems. JDF files allow data communication between a printing press and its management system as well as provide access to print job data and printing press configuration data such as, for example, paper, coverage requirements, colors (inks), web width, ribbon width, web path, ribbon path, product fold, skip/tab slitter requirements and former board position. JDF files are created and sent to the printing press by print planning systems. 
         [0014]      FIG. 1  schematically shows an exemplary embodiment of a printing press  100 , which can be automatically reconfigured from a current print job to a next print job. Printing press  100  includes a splicer  13 , an infeed unit  17 , print units  18  to  21 , a dryer  22 , a cooling unit  23 , a folder superstructure  26  and a delivery unit  32 . Printing press  100  also includes a planning computer  10  and a controller  11 . 
         [0015]    Splicer  13  mounts and splices a roll  14  of a new web  12  onto an end of a web  16 , which is fed from a mounted roll  15 . Rolls  14 ,  15  may be of any diameter and any width. New web  12  is used in the next print job and web  16  is used in the current print job. In order to attach new web  12  to the depleting, almost used-up, web  16 , an adhesive patch may be applied, via splicer  13 , to join the two webs. 
         [0016]    Upon exiting splicer  13 , web  16  travels to infeed unit  17 . Infeed unit  17  feeds web  16  to a sequence of printing units  18 ,  19 ,  20 ,  21 . The number of printing units is shown in the exemplary embodiment as four, but could be higher or lower, depending on the different job requirements for printing press  100 . 
         [0017]    Web  16  then travels, in the exemplary embodiment, through dryer  22 , which is positioned downstream from printing units  18 ,  19 ,  20 ,  21 . Dryer  22  is used to apply heat to the passing web  16  to dry the ink applied by printing units  18 ,  19 ,  20 ,  21 . After passing through dryer  22 , web  16  is fed to cooling unit  23 , for passage between water cooled rollers  24  before entry into folder superstructure  26 . 
         [0018]    In folder superstructure  26 , web  16  is longitudinally slit into a plurality of ribbons  27  by slitters  25 , which are movable via operably connected actuators  33  (see  FIG. 2 ). The direction at which web  16  is moving and at which slitters  25  slit web  16  is identical. Slitters  25  can longitudinally slit web  16  via any of known slitting methods, for example, a knife-cut, a shear-cut or a burst-cut. 
         [0019]    After slitting, ribbons  27  are guided to a roller top of former  28 , which is mounted at the infeed of a former board  29 . Once ribbons  27  pass over roller top of former  28 , ribbons  27  are drawn over former board  29  by infeed rollers  30 , which, if driven, may be used to maintain precise web tension in order to minimize web tearing. Former board  29  imparts a longitudinal fold to ribbons  27  as ribbons  27  pass over former board  29 . The newly folded ribbons  27  are then cut by a crosscutter  31  into individual signatures and are guided for input to delivery unit  32 . 
         [0020]    Planning computer  10  is in digital signal communication with controller  11 . Planning computer  10  is used to create and send JDF files to controller  11 . Planning computer  10  and controller  11  may, alternatively, be embodied in a single unit. Controller  11  may be, for example, a computer or circuitry, such as an application-specific integrated circuit (ASIC). Controller  11  is also JDF data compatible. Controller  11  is programmed to receive and monitor, as inputs, the outputs of various sensors as discussed below with respect to  FIGS. 2 and 3 . Controller  11  provides signals to control splicer  13  and folder superstructure  26 , and may be configured to control the entire printing press  100 , which includes various components digitally interconnected via an internal network. 
         [0021]    In one mode of operation, where one roll of web corresponds to a single print job, controller  11 , continuously monitors web consumption. Upon detecting the impending depletion of web  16  rolled onto mounted roll  15 , controller  11  decreases the speed at which web  16  passes through printing press  100  to a certain setup speed. Then, using sensor data and JDF files, controller  11  determines the amount of web  16  left on mounted roll  15  for the current print job in order to successfully activate web splicer  13  and issues a command to splice the web feed from the depleting mounted roll  15  to the unused roll  14  and adjust the circumferential speed of the newly mounted roll  14  to the printing speed. A conventional tail-cutter may be used to remove the loose end of the new roll  14 . Subsequently, using sensor data and JDF files, controller  11  tracks the splicing location of new web  12  to web  16  as new web  12  travels through printing press  100  and timely adjusts the positions of slitters  25  and former board  29  as well as maintain proper web tension via infeed rollers  31  for the new print job. 
         [0022]    In an alternative mode of operation, more than one roll of web may correspond to a single print job. In such a mode of operation, upon detecting the impending depletion of the last roll allocated for and used in the currently running print job, controller  11  will proceed in a similar mode of operation as where one roll corresponds to one print job and treat the last roll as web  16 . 
         [0023]    A plurality of various operation data sensors are included in printing press  100 . The sensors are used to sense, monitor and output quality control data for the web that moves through printing press  100 . The sensors may include, for example, densitometers, color spectrometers, registration sensors, cut-off sensors and fold sensors. The sensors are strategically positioned throughout printing press  100  and configured to sense, monitor and output operating and product quality control parameters such as, for example, printing press speed, printing press operating events, product image density, ink presets, web tension, register marks, ribbon positions, product fold, former board and slitter positions. The sensors are in digital signal communication with controller  11  or planning computer  10  or both. 
         [0024]    Printing press  100  is automatically reconfigured for the next print job if no ribbon path changes take place and if at least two print job configurations are known: a current print job configuration and a next print job configuration. This data is included in two corresponding JDF files: e.g., a first file that corresponds to the current print job and a second file that corresponds to the next print job. The ribbon path data is known to printing press  100  via JDF data. In addition, it is desirable that JDF2 file is available to controller  11  prior to the conclusion of the current print job. 
         [0025]    For example, printing press  100  is configured for a presently running print job via a JDF file, e.g., JDF1. When the next print job requires a different printing press configuration, prior to the conclusion of the current print job, a printing press operator utilizes planning computer  10  to create and transmit the JDF2 file for the next print job to controller  11  for processing. Controller  11  processes the JDF2 file and the sensor data and, without stopping printing press  100 , automatically reconfigures printing press  100  from the current print job configuration to the next print job configuration. Such reconfiguration may include one or more of the following steps: detecting the impending depletion of web feed from mounted roll  15 , slowing printing press  100  to a certain set up speed, activating splicer  13  to splice web  16  from mounted roll  15  to web  12  from roll  14 , adjusting the lateral positions of slitters  25  via slitter actuators  33  (see  FIG. 2 ), changing the position of former board  29  (fold position) and, if necessary, adjusting the web tension via infeed rollers  30 . 
         [0026]      FIG. 2  schematically shows an example of an automatic slitter adjustment for a print job transfer from a wide web  200  to a narrow web  201 . Wide web  200  corresponds to the current print job and narrow web  201  corresponds to the next print job. The current print job data is known via a file JDF1 and the next print job data is known via a file JDF2. Wide web  200  and narrow web  201  both travel in direction Z shown in  FIG. 2 . 
         [0027]    Slitter  25 , in the presently preferred embodiment, includes three slitter blades  25 A,  25 B and  25 C and three associated actuators  33 A,  33 B and  33 C. In this presently preferred embodiment, the three slitter blades  25 A,  25 B and  25 C can be moved laterally via respective operably connected actuators  33 A,  33 B and  33 C. The number of slitters  25  and actuators  33  is shown as three, but as one of skill in the art will readily recognize, could be greater or lesser, depending on the different job requirements for printing press  100 . 
         [0028]    In the example shown in  FIG. 2 , wide web  200  (the current job web) is 40 inches wide. X 1 , X 2  and X 3  represent the lateral positions of slitters  25 A,  25 B,  25 C for the current printjob. Wide web  200  is slit into four different ten inch ribbons. For the present job in this example, slitter  25 A is laterally positioned at the X 1  position, which is 10 inches from an edge  202  of wide web  200 , slitter  25 B is laterally positioned at the X 2  position, which is 20 inches from the edge  202  and slitter  25 C is laterally positioned at the X 3  position, which is 30 inches from the edge  202 . The lateral positions of slitters  25 A (X 1 ),  25 B (X 2 ) and  25 C (X 3 ), the current print job data and the current printing press configuration are known to controller  11  via the JDF  1  file. 
         [0029]    In the example shown in  FIG. 2 , narrow web  201  is 20 inches wide for the next print job and Y 1 , Y 2  and Y 3  represent the desired lateral positions of slitters  25 A,  25 B,  25 C so that narrow web  201  will be slit into four different five inch ribbons. Thus, in this example, for the next print job, slitter  25 A will be laterally positioned at the Y 1  position, which is 5 inches from an edge  203  of narrow web  201  (15 inches from the edge  202 ), slitter  25 B will be laterally positioned at the Y 2  position, which is 10 inches from the edge  203  (20 inches from the edge  202 ) and slitter  25 C will be laterally positioned at the Y 3  position, which is 15 inches from the edge  203  (25 inches from the edge  202 ). The desired lateral positions of slitters  25 A (Y 1 ),  25 B (Y 2 ) and  25 C (Y 3 ), the new print job data and the new printing press configuration are known to controller  11  via the JDF2 file. 
         [0030]      FIG. 2  shows that wide web  200  includes register marks  206  and  207  and that narrow web  201  includes register marks  208  and  209 . Sensors  204 ,  205  detect the register marks  206 ,  207 , respectfully, which indicate the beginning of a transition web distance D and provide controller  11  with a signal of the impending web change from wide web  200  to narrow web  201 . Subsequently, upon detection of register marks  208 ,  209 , sensors  204 ,  205  alert controller  11 , for example, that the slitting of narrow web  201  according to the JDF2 file is currently taking place and/or that the end of transition web distance D has been reached. 
         [0031]    In addition, sensors installed in splicer  13  can alert controller  11  of the splicing of narrow web  201  onto wide web  200 . Such alert signal(s) may include, for example, splicing operation data such as the exact time and web speed at which the splicing operation took place. Also, sensors, strategically positioned throughout printing press  100 , can notify controller  11  of the current location, within printing press  100 , of the edge of narrow web  201  spliced onto wide web  200  and allow controller  11  to track the edge of narrow web  201  throughout printing press  100 . Using splicing data, tracking data, JDF files and sensor data, controller  11  can calculate the exact time that narrow web  201  reaches various units within printing press  100  such as, for example, folder superstructure  26 . Once that time is known, controller  11 , using the sensor data and the JDF files, can calculate the new configuration information including the desired parameters, the timing for readjustment and the rate of readjustment of printing press  100  components such as, for example, slitters  25 A,  25 B,  25 C, former board  29  and infeed rollers  30 . When the desired parameters, the timing for readjustment and the rate of readjustment of slitters  25 A,  25 B,  25 C, former board  29  and infeed rollers  30  are calculated, controller  11  issues commands to reconfigure printing press  100 . 
         [0032]    During printing, wide web  200  moves through printing press  100  at a designated transition velocity V, e.g., one meter per second (1 m/s). The transition velocity V is the maximum speed that is safe for lateral movement of slitters  25 A,  25 B,  25 C without tearing the web or impairing the necessary web tension. The transition velocity V is known to controller  11  via the JDF file or sensor data. The transition velocity V may be different for different types of webs or different print jobs. 
         [0033]    In operation, wide web  200  will reach a transition web distance D, e.g., two meters remaining from an end of an almost depleted wide web  200 , at a particular point in time. The transition web distance D is the minimum amount of web, when it is traveling at a certain transition velocity V or a minimum setup speed, that is necessary for safe readjustment of slitters  25 A,  25 B,  25 C and former board  29  without tearing the web or impairing the necessary web tension. The amount of transition web distance D is calculated by controller  11  via the JDF file or sensor data. The transition web distance D may be different for different types of webs or different print jobs. 
         [0034]    Since the transition web distance D, the transition velocity V, the current position (X 1 , X 2 , X 3 ) and desired position (Y 1 , Y 2 , Y 3 ) of slitters  25 A,  25 B,  25 C and the print job data and the printing press configuration data for both print jobs are known to controller  11 , in operation, controller  11  calculates a transitioning time T and the rate of lateral movement for slitters  25 A,  25 B,  25 C. Once the transitioning time T and the rate of lateral movement for slitters  25 A,  25 B,  25 C are known and the transition web distance D is detected by sensors  204 ,  205 , controller  11  begins to laterally reposition slitters  25 A,  25 B,  25 C for slitting of narrow web  201  from the X 1 , X 2 , X 3  positions to the Y 1 , Y 2 , Y 3  positions as disclosed in the JDF2 file. 
         [0035]    Three scenarios are possible for transition. First, it is possible that when the web reaches the end of the transition web distance D, slitters  25 A,  25 B,  25 C will have completed their lateral repositioning movement from the X 1 , X 2 , X 3  positions to the Y 1 , Y 2 , Y 3  positions. Second, it is possible that slitters  25 A,  25 B,  25 C, located at the positions X 1 , X 2 , X 3 , may not completely reposition to the Y 1 , Y 2 , Y 3  positions by the time the web reaches the end of transition web distance D, but instead will reach the Y 1 , Y 2 , Y 3  positions after the transition to narrow web  201 . This is possible if the lateral positions of slitters  25 A,  25 B,  25 C are within the width of narrow web  201  at the time when the transition to narrow web  201  reaches slitters  25 A,  25 B,  25 C. In this scenario, the transition time may be extended. Third, it is possible that slitters  25 A,  25 B,  25 C, located at the positions X 1 , X 2 , X 3 , may reach the Y 1 , Y 2 , Y 3  positions before narrow web  201  reaches slitters  25 A,  25 B,  25 C. In this scenario, the transition time is shortened. 
         [0036]    In order to minimize web waste and optimize printing press efficiency, controller  11  will use sensor and the JDF files to determine the optimal method of readjusting slitters  25 A,  25 B,  25 C (before, at or after slitters  25 A,  25 B,  25 C reach the end of transition web distance D) and execute the slitter adjustment accordingly. 
         [0037]    In one embodiment, controller  11  uses the formula: T=D/V to calculate the transition time T that it would take for narrow web  201  to travel the transition web distance D at a given transition velocity V. For example, when the transition web distance D is 2 meters and the transition velocity V is 1 meters/second, it will take 2 seconds for wide web  200  to travel the transition web distance D. 
         [0038]    The lateral distance LD, which is the amount of lateral movement that each individual slitter of slitters  25  will move from the current positions (X 1 , X 2 , X 3 ) to the new desired lateral positions (Y 1 , Y 2 , Y 3 ), is also be known to controller  11 . In the  FIG. 2  example, the lateral distance LD for slitter  25 A is five inches, the lateral distance LD for slitter  25 B is zero inches and the lateral position LD for slitter  25 C is five inches. 
         [0039]    In the  FIG. 2  example, since the transition velocity V is 1 m/s, the lateral distance LD is five inches for slitters  25 A,  25 C, the transition time T is two seconds and the transition web distance D is two meters, slitters  25 A,  25 C will laterally move from the positions X 1 , X 3  to the positions Y 1 , Y 3  at the rate of 2.5 inches per second of travel along the transition distance D. The cut-curve path traveled by slitters  25 A,  25 C through this transition will resemble an inward parabolic curve. 
         [0040]    The maximum lateral speed of slitters  25 A,  25 B,  25 C will be obtained via known data such as, for example, JDF data for a given web type. 
         [0041]    The newly introduced narrow web  201  is advanced through printing press  100  by the preceding wide web  200 , which pulls the narrow web  201  as wide web  200  travels through printing press  100 . 
         [0042]    Reconfiguration of printing press  100 , from wide web  200  to narrow web  201 , will be accomplished if no ribbon path changes are needed. The ribbon path will be known to printing press  100  via at least one of the JDF files. 
         [0043]      FIG. 3  schematically shows an example of an automatic slitter adjustment for a print job transfer from a narrow web  300  to a wide web  301 . The current print job data is known via the JDF1 file and the next print job data is known via the JDF2 file. Narrow web  300  and wide web  301  are both traveling in direction Z. 
         [0044]    In the example shown in  FIG. 3 , narrow web  300  (the current job web) is 20 inches wide and X 1 , X 2 , X 3  represent the current lateral positions of slitters  25 A,  25 B,  25 C for the current print job, which slit narrow web  300  into four different five inch ribbons. For the present job, the X 1  position is 5 inches from an edge  302  of narrow web  300 , the X 2  position is 10 inches from the edge  302  and the X 3  position is 15 inches from the edge  302 . The lateral positions of slitters  25 A (X 1 ),  25 B (X 2 ) and  25 C (X 3 ), the current print job data and the current printing press configuration are known to controller  11  via the JDF1 file. 
         [0045]    In the example shown in  FIG. 3 , for the next print job, wide web  301  is 40 inches wide and Y 1 , Y 2  and Y 3  represent the desired lateral positions of slitters  25 A,  25 B,  25 C for the next print job so that wide web  301  will be slit into four different ten inch ribbons. Thus, the Y 1  position is 10 inches from an edge  303  of wide web  301 , the Y 2  position is 20 inches from the edge  303  and the Y 3  position is 30 inches from the edge  303 . The desired lateral positions of slitters  25 A (Y 1 ),  25 B (Y 2 ),  25 C (Y 3 ), the new print job data and the new printing press configuration are known to controller  11  via the JDF2 file. 
         [0046]      FIG. 3  shows register marks  312  and  313  on narrow web  300  and register marks  314  and  315  on wide web  301 . Sensors  306 ,  307  detect register marks  312 ,  313 , respectfully, which indicate the beginning of the transition web distance D and provide controller  11  with a signal of the impending web change from narrow web  300  to wide web  301 . Upon detection of register marks  314 ,  315 , sensors  306 ,  307  alert controller  11 , for example, that slitting of wide web  301  according to the JDF2 file is currently taking place and/or that the end of a ramp-cut has been reached and/or that the end of transition web distance D has been reached. 
         [0047]    In addition, sensors installed in splicer  13  can alert controller  11  of the splicing of wide web  301  onto narrow web  300 . Unlike the exemplary slitter adjustment in  FIG. 2 , the switch from narrow web  300  to wide web  301  necessitates a ramp-cut, via splicer  13 , on wide web  301  as wide web  301  is pulled through printing press  100  by narrow web  300 . Areas cut from wide web  301  are designated by reference numbers  304  and  305 . 
         [0048]    Upon splicing of wide web  301  onto narrow web  300 , sensors installed in splicer  13  can alert controller  11  of the splicing of wide web  301  onto narrow web  300 . Such alert signal(s) may include such as, for example, the ramp-cut details, the exact time and the web speed at which the splicing operation took place. 
         [0049]    Also, sensors, strategically positioned throughout printing press  100 , can notify controller  11  of the current location, within printing press  100 , of the edge of wide web  301  spliced onto narrow web  300  and allow controller  11  to track the edge of wide web  301  throughout printing press  100 . Using splicing data, tracking data, JDF files and sensor data, controller  11  can calculate the exact time that wide web  301  reaches various units within printing press  100  such as, for example, folder superstructure  26 . Once that time is known, controller  11 , using the sensor data and the JDF files, can calculate the new configuration information including the desired parameters, the timing for readjustment and the rate of readjustment of printing press  100  components such as, for example, slitters  25 A,  25 B,  25 C, former board  29  and infeed rollers  30 . When the desired parameters, the timing for readjustment and the rate of readjustment of slitters  25 A,  25 B,  25 C, former board  29  and infeed rollers  30  are calculated, controller  11  issues a command to reconfigure printing press  100 . 
         [0050]    During printing, narrow web  300  moves through printing press  100  at a transition velocity V, e.g., one meter per second (1 m/s) and reaches the transition web distance D of two meters remaining from an end of an almost depleted narrow web  300  at a particular point in time. The transition web distance D, the transition velocity V, the current position (X 1 , X 2 , X 3 ) and the desired position (Y 1 , Y 2 , Y 3 ) of slitters  25 A,  25 B,  25 C and the print job data and the printing press configuration data for both jobs are known to controller  11 . Thus, controller  11  calculates the transitioning time T and the rate of lateral movement for slitters  25 A,  25 B,  25 C. Once the transitioning time T and the rate of lateral movement for slitters  25 A,  25 B,  25 C are known and the transition web distance D is detected by sensors  306 ,  307 , controller  11 , if necessary, begins to laterally reposition slitters  25 A,  25 B,  25 C, for slitting wide web  301 , from the X 1 , X 2 , X 3  positions to the Y 1 , Y 2 , Y 3  positions as disclosed in JDF2 file. 
         [0051]    The same three scenarios exist with respect to the transition of the slitters, except that if any of the slitters need to be positioned to a point outside the dimension of the current web, the transition will never take less than time T. 
         [0052]    The  FIG. 3  example, like the  FIG. 2  example, will take 2 seconds for narrow web  300  to travel the transition web distance D, based on the same simple formula. The lateral distance LD for slitter  25 A is five inches, the lateral distance LD for slitter  25 B is zero inches and the lateral distance LD for slitter  25 C is five inches. 
         [0053]    As with the  FIG. 2  example, slitters  25 A,  25 C will laterally move at the rate of 2.5 inches per second of travel along the transition distance D. The cut-curve path traveled by slitters  25 A,  25 B will resemble an outwards parabolic curve. 
         [0054]    While the present invention has been particularly shown and described with reference to the preferred embodiments and various aspects thereof, it will be appreciated by those of ordinary skill in the art that various changes and modifications may be made without departing from the spirit and scope of the invention. It is intended that the appended claims be interpreted as including the embodiments described herein, the alternatives mentioned above, and all equivalents thereto.