Abstract:
A printing press is provided. The printing press includes a print unit printing a stream of printed products having a first pitch, a pitch changing device and a controller. The pitch changing device includes an upper roller mounted on an upper axle, a lower roller mounted on a lower axle, the upper and lower rollers forming a roller nip and at least one motor driving the upper and lower rollers in opposite directions. The roller nip receives the stream of printed products. The controller is connected to the at least one motor and is configured to decrease an initial velocity of the roller nip to a final velocity using an electronic cam velocity profile and to increase the final velocity of the nip to the initial velocity after releasing the printed products over a longer period of a cycle of the electronic cam velocity profile than decreasing the initial velocity to the final velocity. A method is also provided.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This is a continuation of U.S. application Ser. No. 12/072,947 filed on Feb. 29, 2008, the entire disclosure of which is hereby incorporated by reference herein. 
    
    
     BACKGROUND 
     The present invention relates generally to printing presses and more particularly to printing presses with conveyors altering the pitch of printed products printed in the printing press. 
     U.S. Pat. No. 6,176,485, hereby incorporated by reference herein, discloses a diverting device for a continuous sequence of flat products traveling in a product travel plane. A first product exit path and a second product exit path emerge both from said product travel plane. 
     U.S. Pat. No. 6,405,850 discloses an apparatus for advancing and/or slowing signatures in a printing press. The apparatus and method includes a series of two or more belt drives, where each belt drive includes at least a pair of opposed belts. The belts are preferably timing or toothed belts driven by sprockets. 
     U.S. Pat. No. 6,561,507 discloses a folder apparatus that includes a conveyor and knock-down wheel assembly to receive signatures from, for example, a tape system output. The conveyor and knock-down wheel assembly slow down the signatures from the tape system and create a shingled output stream of signatures. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention provides a printing press including: 
     a print unit printing a stream of printed products, the printed products having a first pitch; and 
     a pitch changing device including;
         an upper roller mounted on an upper axle;   a lower roller mounted on a lower axle, the upper and lower rollers forming a roller nip; and   a motor driving the upper and lower rollers in opposite directions;   the nip receiving the stream of printed products;   the motor varying the velocity of the nip and the printed products using an electronic cam velocity profile so as to alter the first pitch.       

     The present invention also provides a method for changing the velocity of printed products in a product stream including the steps of: 
     moving printed products at a first velocity and a first pitch; 
     rotating a nip of two rollers at the first velocity; 
     receiving the printed products at the nip; and 
     changing the first velocity of the nip and printed products to a second velocity that is different from the first velocity using an electronic cam velocity profile so as to alter the first pitch. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A preferred embodiment of the present invention will be elucidated with reference to the drawings, in which: 
         FIG. 1  shows a printing press according to the present invention; 
         FIG. 2  shows an electronic pitch changing apparatus according to the present invention; 
         FIG. 3  shows a graph of nip linear velocity versus time for the electronic pitch changing apparatus shown in  FIG. 2 ; 
         FIG. 4  shows two of the electronic pitch changing apparatus shown in  FIG. 2 ; 
         FIG. 5  shows a graph of nip linear velocity versus time for the electronic pitch changing apparatus shown in  FIG. 4 ; 
         FIG. 6  shows the electronic pitch changing apparatus shown in  FIG. 2  shingling printed products; 
         FIG. 7  shows another embodiment of the electronic pitch changing apparatus according to the present invention; and 
         FIGS. 8 and 9  show schematically rollers of the electronic pitch changing apparatus in  FIGS. 2 and 7 , respectively. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       FIG. 1  shows a preferred embodiment of a web printing press  100  in accordance with the present invention including a web  101  traveling through a plurality of printing units  112  and a folder  120  providing a plurality of signatures  102 ,  104  to an electronic pitch changing apparatus  10 . 
       FIG. 2  shows an electronic pitch changing apparatus  10  in accordance with the present invention. Electronic pitch changing apparatus  10  includes rollers  20 ,  22 ,  24 ,  26 . Rollers  20  and  22  create a nip  40  and rollers  24  and  26  create a nip  42 . Rollers  20 ,  24  are mounted on axle  62  while rollers  22 ,  26  are mounted on axle  64 . Axle  62  rotates in a clockwise direction while axle  64  rotates in a counter-clockwise direction. Axle  62  is connected to a roller  34 . Axle  64  is connected to a roller  32 . 
     A motor  60  drives a roller  36  and motor  60  is connected to a controller  80 . Roller  36  drives rollers  30 ,  32  and  34  via belt  50 . Roller  34  rotates in the clockwise direction, thus rotating axle  62  in the clockwise direction. Due to the arrangement of belt  50 , roller  32  rotates in the counter-clockwise direction, thus rotating axle  64  in the counter-clockwise direction. Nips  40 ,  42  receive printed products  102 ,  104  and transport printed products  102 ,  104  in a direction X through nips  40 ,  42 . Printed products  102 ′,  104 ′ correspond to printed products  102 ,  104  at a point in time after products  102 ,  104  have passed through electronic pitch changing apparatus  10 . 
     The “pitch” or distance between the head of printed products may be varied by increasing or decreasing the velocity of printed products  102 ,  104 , while printed products  102 ,  104 , are transported through nips  40 ,  42 . Distance (d) traveled by a printed product is equal to the product of the velocity (v) of the product and the time of travel (t), d=v*t. A direct relationship exists between the velocity of a printed product and the distance traveled by the printed product. Accordingly, decreasing the velocity decreases the distance traveled by the product. 
     Motor  60  has an electronic cam velocity profile designed to increase or decrease pitch of printed products  102 ,  104  by increasing or decreasing the velocity of the printed products  102 ,  104 , respectively. The linear velocities of products  102 ,  104  and nips  40 ,  42  when products  102 ,  104  first come into contact with nips  40 ,  42  are the same, initial velocity V 1 . The initial velocity V 1  is changed in accordance with the electronic cam velocity profile in motor  60 . An initial pitch P 1  exists between products  102  and  104  before entering nips  40 ,  42 . As shown in  FIG. 1 , the initial pitch P 1  between products  102 ′ and  104 ′ is decreased to a final pitch P 2  after products  102 ,  104  pass through nips  40 ,  42 . A sensor  70  detects final pitch P 2  between products  104 ′ and  102 ′. Sensor  70  is connected to controller  80 . Controller  80  can control the velocity profile of motor  60  to adjust final pitch P 2  as desired. The electronic cam velocity profile may be similar to the electronic cam velocity profile in U.S. Publication No. 2007/0158903, hereby incorporated by reference herein, which discloses a variable speed motor having a sinusoidal speed variation cycle. 
     As shown in  FIGS. 1 and 2 , cam velocity profile  200  decreases pitch by decreasing the velocities of printed products  102 ,  104  in a product stream. For example, product  104  traveling at an initial velocity V 1  of 2750 FPM will travel 2750 feet in one minute. Product  102  traveling at an initial velocity V 1  of 2750 FPM will also travel 2750 feet in one minute. After decreasing the velocity of product  104  using the electronic pitch changing apparatus  10 , the final velocity V 2  of corresponding product  104 ′ upon exit of apparatus  10  is 1700 FPM, so product  104 ′ will travel 1700 feet in one minute. Product  102  is still moving at an initial velocity V 1  of 2750 FPM. After product  104 ′ is released from apparatus  10 , the pitch between products decreases at a rate of about 1050 feet per minute, the difference between the final velocity V 2  of product  104 ′ and initial velocity V 1  of product  102 . The pitch decreases at this rate until product  102  enters apparatus  10 , and is slowed down in the same manner as product  104 . 
       FIG. 3  shows the linear nip velocity over time charted as cam velocity profile  200 . Profile  200  is a sinusoidal curve. As shown in  FIGS. 2 and 3 , the initial velocity V 1  is decreased to a final velocity V 2 , reducing initial pitch P 1  to final pitch P 2 , thereby decreasing the space between products  102 ′,  104 ′. At entry into nips  40 ,  42  the linear initial velocity V 1  of both nips  40 ,  42  and product  104  is 2750 FPM. Entry of product  104  is indicated by point  202  on cam profile  200  in  FIG. 3 . 
     Motor  60 , following cam velocity profile  200 , reduces the initial velocity V 1 , 2750 FPM of product  104  to final velocity V 2 , 1700 FPM, upon exit of product  104 ′ from apparatus  10 . Motor  60  slows the initial velocity V 1  of nips  40 ,  42  and product  104  to 1700 FPM in 0.018 seconds, indicated by point  206  on cam velocity profile  200 . At point  206 , product  104 ′ exits apparatus  10 . 
     From 0.018 seconds to 0.036 seconds, no products may be transported through nips  40 ,  42 . Following cam velocity profile  200 , motor  60  brings the velocity of nips  40 ,  42  up to 2750 FPM in 0.018 seconds, as indicated by point  204 . At this point, nips  40 ,  42  are ready to receive a subsequent product  102 . Product  102  is slowed down in the same manner as product  104 . The decrease in initial velocity V 1  to final velocity V 2  of products  102  and  104  results in a smaller final pitch P 2  between products  102 ′ and  104 ′ as compared to the initial pitch P 1  between products  102  and  104  as shown in  FIG. 2 . 
       FIG. 4  shows an arrangement  108  of two electronic pitch changing apparatus  10 ,  110 . A single stream of products  103  is split into two product streams A, B by a diverter or stream separator as disclosed in, for example, U.S. Pat. No. 6,176,485. Electronic pitch changing apparatus  110  includes two axles  162 ,  164  connected to rollers  132 ,  134  respectively. Rollers  120  and  124  are mounted on an axle  162  and rollers  122  and  126  are mounted on an axle  164 . Rollers  120  and  122  form a nip  140 . Rollers  124  and  126  form a nip  142 . A motor  160  drives axles  162 ,  164  via rollers  130 ,  132 ,  134 ,  136  and belt  150  and is connected to controller  80 . Sensors  70 ,  72  are also connected to controller  80 . 
     As shown in  FIGS. 4 and 5 , the length of time, nips  40 ,  42  and  140 ,  142  act on products  104 ,  99  and  102 ,  98 , respectively, is the same as the length of time nips  40 ,  42  act on products  104 ,  102  as shown in  FIGS. 2 and 3 , 0.018 seconds. The length of time is dependent upon the velocity of the nips and the length of the printed products. 
     In arrangement  108 , there is more time between products  104 ,  99  and  102 ,  98  entering nips  40 ,  42  and  140 ,  142 , respectively, because a void is left between products when single product stream  103  is split into two product streams A, B. Thus, an initial pitch P 3  between products  104  and  99  and an initial pitch P 5  between products  102  and  98  is greater than the initial pitch P 1  between products  104  and  102  in  FIG. 2 . 
     The increased pitch and subsequent increase in time between products entering nips allows for changes in the cam velocity profile.  FIG. 5  shows the linear nip velocity over time for apparatus  10 ,  110  charted as cam velocity profile  300 . Profile  300  is a non-symmetrical sinusoidal curve. Profile  300  will be described as applied to apparatus  110 ; however, profile  300  may be applied in the same way to apparatus  10  of  FIG. 4 . At an initial time, 0.0 seconds, the linear velocity of both nips  140 ,  142  and product  102  is 2750 FPM. Entry of product  102  into nips  140 ,  142  is indicated by point  302  on cam profile  300 . 
     Motor  160  following cam velocity profile  300  reduces the initial velocity V 1 , 2750 FPM, of product  102  to final velocity V 2 , 1500 FPM, upon exit of product  102 ′ from apparatus  110 . Motor  160  slows the initial velocity V 3  of nips  140 ,  142  and product  102  to 1500 FPM in 0.018 seconds, indicated by point  306  on cam velocity profile  300 . At point  306 , product  102 ′ exits apparatus  110 . 
     From 0.018 seconds to 0.072 seconds, no products may be transported through nips  140 ,  142 . Following cam profile  300 , motor  160  brings the velocity of nips  140 ,  142  up to 2750 FPM in 0.054 seconds, as indicated by point  304 . At this point, nips  140 ,  142  are ready to receive a subsequent product  98 . Product  98  is slowed down in the same manner as product  102 . The decrease in initial velocity V 3  to final velocity V 4  of products  102  and  98  results in a smaller final pitch P 6  between products  102 ′ and  98 ′. Sensor  72  detects final pitch P 6  between products  102 ′ and  98 ′. Controller  80  may adjust the velocity profile of motor  160  to obtain a desired final pitch P 6 . 
     Motor  160  has 0.054 seconds to bring the linear velocity of nips  140 ,  142  up to the initial velocity V 3  of 2750 FPM. This may be advantageous by reducing the amount of RMS torque required by motor  160 . Thus, it may be easier for motors  60 ,  160  to work on separated streams A, B as shown in  FIG. 4  than a single stream of products as shown in  FIG. 2 . Controller  80  can control the velocity profile of motor  160  to adjust final pitch P 6  as desired. 
       FIG. 6  shows electronic pitch changing apparatus  10  shingling products. The velocity V 1  of products  104  and  102  is decreased to a final velocity V 2  in order to overlap products  104 ′,  102 ′ upon exit from apparatus  10 . 
       FIG. 7  shows another preferred embodiment of an electronic pitch changing apparatus  400  in accordance with the present invention. Electronic pitch changing apparatus  400  includes rollers  420 ,  424  mounted on axle  462  and rollers  422 ,  426  mounted on axle  464 . Roller  420  and roller  422  create a continuous nip  440  and roller  424  and roller  426  create a continuous nip  442 . Rollers  420 ,  422 ,  424 ,  426  are surrounded in nip material  522  as shown in  FIG. 9 .  FIG. 9  shows rollers  420  and  422  forming continuous nip  440 . Both rollers  420 ,  422  include nip material  522  mounted around an entire circumference of roller base  520  ( FIG. 9 ) forming a continuous nip  440  as rollers  420 ,  422  rotate on axles  462 ,  464  ( FIG. 7 ). Edge sensors  450  are connected to controller  480  and detect a leading edge of products  404 ,  402  entering nips  440 ,  442 . 
     Alternatively, as shown in  FIG. 8 , rollers  20 ,  22  include nip material  512  mounted on only a portion of the circumference of roller base  510 . Rollers  20 ,  22  create nip  40  when nip material  512  from roller  20  contacts or abuts nip material  512  from roller  22  as rollers  20 ,  22  rotate on axles  62 ,  64  shown in  FIG. 2 . 
     Referring back to  FIG. 7 , axle  462  rotates in a clockwise direction while axle  464  rotates in a counter-clockwise direction. A motor  460  drives axle  464  directly and a motor  461  drives axle  462  directly. Motors  460 ,  461  are connected to a controller  480 . 
     Electronic pitch changing apparatus  400  works similarly to electronic pitch changing apparatus  10  in  FIG. 2  to vary an initial pitch P 7  between products  404 ,  402 . However, an edge sensor  450  will detect the leading edge of products  404 ,  402  entering nips  440 ,  442 . Controller  480  keeps electronic cam profiles of motors  460 ,  461  accurately in phase with products  404 ,  402  to vary initial pitch P 7  to a final pitch Pg between products  404 ′ and  402 ′. Controller  480  automates the initial timing and may reduce interaction and confusion for an operator. 
     The continuous nips advantageously may be used on all folder cutoff lengths since the length of the nips does not need to be resized. Continuous nips also advantageously provide flexibility since as little or as much of the nip surface may be used as desired. 
     The cam profile may be sinusoidal, symmetric or asymmetric. Cam profiles of individual motors do not have to be identical when a diverter or stream separator is used. 
     In the preceding specification, the invention has been described with reference to specific exemplary embodiments and examples thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of invention as set forth in the claims that follow. The specification and drawings are accordingly to be regarded in an illustrative manner rather than a restrictive sense.