Abstract:
An apparatus for decelerating a signature comprises a movable belt arrangement, and a motor coupled to the movable belt arrangement for controllably moving the movable belt arrangement through a cyclical velocity profile. The movable belt arrangement is moved through a signature engaging section with the cyclical velocity profile causing the motor to decelerate the movable belt arrangement from a first speed to a second speed while engaging a signature in the signature engaging section. The signature enters the signature engaging section at the first speed, and leaves the signature engaging section at the second speed, lower than the first speed. The cyclical velocity profile causes the movable belt arrangement to accelerate upon the signature leaving the signature engaging section, back to the first speed, prior to a next signature entering the signature engaging section.

Description:
BACKGROUND OF THE INVENTION 
     In a printing operation, signatures are moved through a printing press at a maximum press speed that is considerably faster than can be accommodated in downstream equipment such as folders. Typically, signature speed is reduced by approximately 50% before input to a folder. 
     In known printing press equipment, a deceleration mechanism is utilized to decelerate signatures as they exit a printing press, and prior to input to a folder. The deceleration mechanism implements mechanical structures that engage and decelerate the individual signatures. The constant stress of multiple decelerations of substantial numbers of signatures, as are encountered in commercial printing operations, causes durability problems with known deceleration solutions. Moreover, in some known devices, the abrupt nature of the signature deceleration results in product defects. 
     SUMMARY OF THE INVENTION 
     The present invention provides a new and improved apparatus and method for decelerating a signature. 
     In a first exemplary embodiment of the present invention, an apparatus for decelerating a signature comprises a movable belt arrangement, and a motor coupled to the movable belt arrangement for controllably moving the movable belt arrangement through a cyclical velocity profile. Pursuant to a feature of the present invention, the movable belt arrangement is moved through a signature engaging section with the cyclical velocity profile causing the motor to decelerate the movable belt arrangement from a first speed to a second speed while engaging a signature in the signature engaging section. The signature enters the signature engaging section at the first speed, and leaves the signature engaging section at the second speed, lower than the first speed. The cyclical velocity profile causes the movable belt arrangement to accelerate upon the signature leaving the signature engaging section, back to the first speed, prior to a next signature entering the signature engaging section. 
     In a second exemplary embodiment of the present invention, a method for decelerating a signature comprises the steps of providing a movable belt arrangement, and controllably moving the movable belt arrangement through a cyclical velocity profile. Pursuant to a feature of the present invention, the cyclical velocity profile causes the movable belt arrangement to decelerate from a first speed to a second speed while engaging a signature in a signature engaging section, the signature entering the signature engaging section at the first speed, and leaving the signature engaging section at the second speed, lower than the first speed. The cyclical velocity profile subsequently accelerates the movable belt arrangement upon the signature leaving the signature engaging section, back to the first speed, prior to a next signature entering the signature engaging section. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a motor driven belt arrangement used as a signature deceleration mechanism, according to a feature of the present invention. 
         FIG. 1   a  is a segment of the perspective view of  FIG. 1 , showing a gripper embodiment of the present invention. 
         FIG. 1   b  is a segment of the perspective view of  FIG. 1 , showing a pad embodiment of the present invention. 
         FIG. 2  is a perspective view of a two-motor belt arrangement for a signature deceleration mechanism, according to a feature of the present invention. 
         FIG. 3  is a graph showing motor velocity profiles for the belt arrangements of  FIGS. 1 and 2 . 
         FIGS. 4  ( a )-( e ) show a side view progression of signature travel through the two-motor belt arrangement of  FIG. 2 . 
         FIG. 5  is a schematic illustration of a multi-stage signature deceleration arrangement, according to a feature of the present invention. 
         FIG. 6  is a graph showing motor velocity profiles for the multi-stage signature deceleration arrangement of  FIG. 5 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings, and initially to  FIG. 1 , there is shown a perspective view of a motor driven movable belt arrangement used as a signature deceleration mechanism, according to a feature of the present invention. A variable speed motor  1  is coupled to a drive sprocket assembly  2 . A pair of belts  7  is arranged to extend around the drive sprocket assembly  2  for circulation through a path defined by the drive sprocket assembly  2  and idler sprockets  3 ,  4 ,  5 . A pair of pins  6  is provided, each one of the pair  6  is mounted on a respective one of the belts  7  to register and align a signature  8  carried by the belts  7  from the idler sprockets  3  to the idler sprockets  5 . 
       FIG. 1   a  shows an alternative embodiment for the pins of  FIG. 1 . In the embodiment of  FIG. 1   a , the structure arranged to register and align the signature  8  comprises a pair of grippers  60 . 
       FIG. 1   b  shows a further alternative embodiment for the pins of  FIG. 1 . In the embodiment of  FIG. 1   b , the structure arranged to register and align the signature  8  comprises a pair of pads  61 . 
     According to a feature of the present invention, the variable speed motor  1  is controlled to operate in a sinusoidal speed variation cycle, as illustrated, for example, by the solid line velocity profile curve  14  depicted in  FIG. 3 . The speed of the motor  1  is at a maximum when the pins  6  are at a predetermined distance downstream from the idler sprockets  3 , and first contact an incoming signature  8  moving at a high printing press speed (point  17  on the graph of  FIG. 3 ). The speed of the motor  1  is controlled to continuously decelerate (points  17  to  18  on the graph of  FIG. 3 ), until the belts  7  are moved to displace the signature  8  from the idler sprockets  3  to the idler sprockets  5 , for discharge of the signature  8  to a downstream piece of equipment. 
     At point  18 , the speed of the motor  1  is at a minimum, to match the operating speed of the downstream equipment. After discharge of the signature  8 , the speed of the motor  1  is controlled to accelerate back to its maximum speed (points  18  to  20  on the graph of  FIG. 3 ). At point  20 , the motor  1  has moved the pins  6  back past the idler sprockets  3 , and in a position to receive another signature  8  from the printing press for deceleration. 
     Referring now to  FIG. 2 , there is shown a perspective view of a two-motor movable belt arrangement for a signature deceleration mechanism, according to a feature of the present invention. A first variable speed motor  1 ′ is coupled to a drive sprocket assembly  9 . A first pair of belts  7 ′ is arranged to extend around the drive sprocket assembly  9  for circulation through a path defined by the drive sprocket assembly  9  and idler sprockets  3 ′,  4 ′,  5 ′. A first pair of pins  6 ′ is provided, each one of the pins  6 ′ is mounted on a respective one of the belts  7 ′ to register and align a first signature  8 ′ carried by the belts  7 ′ from the idler sprockets  3 ′ to the idler sprockets  5 ′. 
     A second variable speed motor  11  is coupled to a drive sprocket assembly  13 . The drive sprocket assembly  13  is arranged to drive a second pair of belts  12  through a path defined by the drive sprocket assembly  13  and the idler sprockets  3 ″,  4 ″,  5 ″. A second pair of pins  6 ″ is provided, each one of the pair  6 ″ is mounted on a respective one of the belts  12  to register and align a second signature  8 ″ carried by the belts  12  from the idler sprockets  3 ″ to the idler sprockets  5 ″. The second pair of belts  12  is offset from and interspersed between the first pair of belts  7 ′ such that the pairs of belts  7 ′ and  12  are moved independently from one another by the respective motors  1 ,  11 . 
     According to a feature of the present invention, the variable speed motors  1 ,  11  are controlled to operate in sinusoidal speed variation cycles that are out of phase from one another. As noted above, the solid line velocity profile curve  14  depicted in  FIG. 3  represents the velocity profile for the motor  1 . The dotted line velocity profile curve  15  depicted in  FIG. 3  represents the velocity profile for the motor  11 . As clearly illustrated in the graphs of  FIG. 3 , the velocity profile  14  for the first motor  1  is at a maximum velocity  17  occurring at the same time as the minimum velocity  16  of the velocity profile  15  for the second motor  11 . 
     Similarly, the minimum velocity  18  of the curve  14 , for the first motor  1 , occurs at the same time as the maximum velocity  19  of the velocity curve  15  for the second motor  11 , and so on. The velocity curve  14  returns to a maximum velocity, once again at point  20 , at the end of a period P ( 21  on the graph of  FIG. 3 ). The frequencies of the curves  14 ,  15  are each twice the frequency of signature entry to the two motor belt arrangement. 
       FIGS. 4  ( a )-( e ) show a side view progression of signature travel through the two-motor belt arrangement of  FIG. 2 .  FIG. 4(   a ), at time t=0, shows a pin  22  from the first pair of belts  7 ′ when the motor  1  is at the maximum velocity ( 17  from the graph of  FIG. 3) . At this time, a signature  24  (at a maximum speed) is entering the belt arrangement, and contacts the pins  22 . At the same time, pin  23 , of the second pair of belts  12  is at a minimum velocity ( 16  from the graph of  FIG. 3 ) and the deceleration of the corresponding signature  25  is complete. 
       FIG. 4(   b ), at time t=0.006 seconds, shows the pin  23  of the second belt pair  12  rotating around idler sprocket  42  (at point  44  of  FIG. 3) , out of the path of the signature  25 . The second belt pair  12  is then in an accelerating mode to move the pin  23  back toward the input end of the two belt system. At this point in the progression, the pin  22  of the first belt pair  7 ′ is acting to decelerate the signature  24 . 
     In  FIG. 4(   c ), at time t=0.022 seconds, there is depicted the state of the two belt system of  FIG. 2  at point  45  of the graph of  FIG. 3 . A next pin  33  on the accelerating second belt pair  12  rotates around idler sprocket  43 , into the path of a next incoming signature  32 , while the pin  22  of the first belt pair  7 ′ continues to decelerate the corresponding signature  24 . The signature  25 , previously abutting the pin  23  in  FIG. 4(   b ), is transported away from the two belt system, at a fully decelerated speed. Meanwhile, the pin  23  of the second belt pair  12  continues to be accelerated by the motor  11 . 
     In  FIG. 4(   d ), at point  46  of the graph of  FIG. 3 , the pin  33  of the second pair of belts  12 , is positioned ahead of the incoming signature  32 . 
     Finally, in  FIG. 4(   e ), the second pair of belts  12  continues to be accelerated until the pin  33  has engaged the signature  32  (point  19  of the graph of  FIG. 3) . Thereafter, the second belt pair  12  starts to decelerate. At the same time, the first pair of belts  7 ′ is fully decelerated (point  18  of the graph of  FIG. 3 ), as is the corresponding pin  22  and signature  24 . 
     This sequence of events continues such that alternative signatures, each at a maximum speed, are engaged by pins, alternatively, of the first and second pairs of belts  7 ′ and  12 . The belt pairs operate through alternate periods of acceleration and deceleration, 180 degrees out of phase from one another, the decelerate each of the incoming signatures, from a press speed to a slower speed suitable for operation of downstream equipment. 
     Referring now to  FIG. 5 , there is shown a schematic illustration of a multi-stage signature deceleration arrangement, according to another feature of the present invention. The solution provided by the arrangement of  FIG. 5  comprises a sequence of velocity reduction belt arrangements, each operating according to a cyclical velocity profile, to reduce the speed of each signature in stages, as the signatures travel through the sequence of belts. As each signature traverses each stage it is decelerated by a predetermined amount in each stage. 
     In the example of  FIG. 5  there is shown a four stage deceleration arrangement including drive cylinders  103 ,  105 ,  107   109 . A first motor  101  is coupled to each of a gear box  102  and the drive cylinder  107 . The gear box  102  is, in turn, coupled to the drive cylinder  103 . The gear ratio provided by the gear box  102  is such that the surface velocity of the drive cylinder  103  is proportionately faster than the surface velocity of the drive cylinder  107 , as will be described in greater detail below. 
     A second motor  113  is coupled to each of a gear box  112  and the drive cylinder  109 . The gear box  112  is, in turn, coupled to the drive cylinder  105 . The gear ratio provided by the gear box  112  is such that the surface velocity of the drive cylinder  105  is proportionately faster than the surface velocity of the drive cylinder  109 , as will also be described in greater detail below. 
     Each of the drive gears  103 ,  105 ,  107 ,  109  dives a corresponding endless belt  104 ,  106 ,  108 ,  110  around respective idler cylinders  120 ,  122 ,  124 ,  126 . Moreover, a plurality of idler belt arrangements  128 ,  130 ,  132 ,  134  is arranged, one each in an opposed relation to a corresponding one of the endless belt  104 ,  106 ,  108 ,  110 . A signature  111  is received between the pairs of opposed endless belts  104 ,  106 ,  108 ,  110  and idler belt arrangements  128 ,  130 ,  132 ,  134 , for transport in the direction of travel indicated in  FIG. 5 , and gradual deceleration from belt to belt. 
       FIG. 6  is a graph showing motor velocity profiles  114 ,  115 ,  116 ,  117 , for the multi-stage signature deceleration arrangement of  FIG. 5 . The velocity profiles  114 ,  115 ,  116 ,  117  correspond to the velocities of the belts  104 ,  106 ,  108 ,  110 , respectively, as they are driven by the respective motors  101 ,  113 . The motors  101 ,  113  are each controlled to be operated through a sinusoidal velocity cycle and the motors  101 ,  113  are operated 180 degrees out of phase from one another. 
     As the signature  111  exits the opposed belts  104 ,  128  it will be traveling at 85.4% of the entrance velocity as the signature  111  follows the velocity profile  114 . The signature then enters the opposed belts  106 ,  130  and follows the velocity profile  115 . The opposed belts  106 ,  130  operate to decelerate the signature further from 85.4% of the original entrance velocity, to 70.7% of the entrance velocity. 
     As the signature  111  travels through the opposed belts  106 ,  130 , the belt  104  is driven to accelerate back to 100% velocity (velocity profile  114 ) to match the entrance velocity of a next entering signature. After travel through the opposed belts  106 ,  130 , the signature  111  enters the opposed belts  108 ,  132 , and decelerates from 70.7% to 60.4% of the entrance velocity, according to the velocity profile  116 . Finally, the signature  111  travels through the opposed belts  110 ,  134  according to velocity profile  117  to further reduce the velocity to 50% of the entrance velocity. Thus, the signature velocity is incrementally reduced 50% in four stages. 
     Subsequent to transport of a signature, each of the driven belts  106 ,  108 ,  110  is accelerated back to the initial velocity to match the velocity of a next incoming signature. The velocity profiles  114 ,  116  are in phase with one another, with an offset in nominal velocity. The offset is achieved by the gearbox  102  in between the motor  101  and the driven cylinder  103 . The velocity profiles  115 ,  117  are also in phase, but offset in nominal velocity by the gear box  112 . 
     As noted above, the motors  101 ,  113   101 ,  113  are each controlled to be operated through a sinusoidal velocity cycle and the motors  101 ,  113  are operated 180 degrees out of phase from one another. Additional stages can be added with either additional motors or gearboxes. 
     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 the 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.