Abstract:
An apparatus for varying the speed of printed products is provided. The apparatus includes a nip roll rotatable about a nip roll axis and an eccentric assembly external of the nip roll coupled to the nip roll coincident with the nip roll axis. The eccentric assembly is adapted to eccentrically move the nip roll. A method of varying the speed of a printed product in a printing press is also provided.

Description:
The present invention relates to an apparatus for varying the speed of printed products having an external eccentric assembly. 
     BACKGROUND 
     U.S. Pat. No. 6,302,391, which is hereby incorporated by reference herein, discloses an apparatus for varying the speed of flat products, wherein a copy is first engaged by high speed conveyor belts. The copy then passes through tension rollers while at the same time is taken over by liner sections of deceleration rollers where a trailing end of the copy leaves the nip between the tension rollers. Downstream of the nip, the high speed conveyor belts gradually diverge; the copy is no longer touched by high speed belts and can be braked by the liner sections, which cover part of the circumference of the deceleration rollers. The release of the copy by the deceleration rollers takes place at the same moment when the leading edge of the copy is engaged by the slow conveyor belts. The slow conveyor belt system is used to transport the copy to the second longitudinal folders. With this type of configuration, the deceleration rollers may be adjusted by moving the support for one of the deceleration rollers to modify the gap between the liner sections. This adjustment of the slow conveyor belt system also adjusts the accessibility to the high speed conveyor belts. 
     SUMMARY OF THE INVENTION 
     An apparatus for varying the speed of printed products is provided. The apparatus includes a nip roll rotatable about a nip roll axis and an eccentric assembly external of the nip roll coupled to the nip roll coincident with the nip roll axis. The eccentric assembly is adapted to eccentrically move the nip roll. 
     A method of varying the speed of a printed product is also provided. The method includes contacting a signature traveling at a first speed with nip rolls; eccentrically moving the nip rolls with eccentric assemblies that are external of the nip rolls; and releasing the signature from the nip rolls at a second speed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is described below by reference to the following drawings, in which: 
         FIG. 1  schematically shows a side view of a signature velocity changing apparatus according to an embodiment of the present invention; 
         FIG. 2  schematically shows a perspective view of an upper section of the signature velocity changing apparatus shown in  FIG. 1 ; 
         FIGS. 3   a  to  3   c  schematically show a progression of the upper section of the signature velocity changing apparatus shown in  FIGS. 1 and 2  contacting and decelerating a signature; 
         FIGS. 4   a  to  4   c  schematically show a progression of the upper section of the signature velocity changing apparatus shown in  FIGS. 1 and 2  contacting and accelerating a signature; 
         FIG. 5  schematically shows a perspective view of an upper section of a signature velocity changing apparatus according to another embodiment of the present invention; and 
         FIG. 6  shows a drive arrangement for driving the upper section shown in  FIG. 5 . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       FIG. 1  shows a side view of a printed product velocity changing apparatus  10  according to an embodiment of the present invention, which may accelerate or decelerate printed products, such as signatures  12 , in post process equipment in the graphics industry. For example, velocity changing apparatus  10  may be used in a folder similar to the folding system disclosed in incorporated by reference U.S. Pat. No. 6,302,391 B1 to decelerate or accelerate signatures. Apparatus  10  may include an upper section  11  and a lower section  13  that are substantially identical, in mirror image. Upper section  11  includes an upper roll  14  eccentrically rotatable about an axis d and an eccentric assembly  50  coupled to upper roll  14  coincident with axis d. Lower section  13  includes a lower roll  15  rotatable about an axis e and an eccentric assembly  51  coupled to lower roll  15  coincident with axis e. Eccentric assembly  50  includes two links  16 ,  18  and two external eccentric shafts  20 ,  22  and eccentric assembly  51  includes two links  17 ,  19  and two external eccentric shafts  21 ,  23 . Each roll  14 ,  15  includes a respective nip segment  24 ,  25  and transporting signatures  12  at a nip  31  attached to an outer surface of a respective nip roll body  26 ,  27 . Nip segments  24 ,  25  may each be formed by a single continuous material or two or more parallel strips of material. 
       FIG. 2  shows a perspective view of upper section  11 . Lower section  13  ( FIG. 1 ) is configured in the same manner as upper section  11 . External eccentric shaft  20  may include two end sections  28 ,  30  and an interior section  29  and external eccentric shaft  22  may include two end sections  32 ,  34  and an interior section  33 . Links  16 ,  18  are coupled to both interior sections  29 ,  33 . End sections  28 ,  30  are each concentrically rotatably coupled to support structures at an axis b. Interior section  29  is mounted eccentrically with respect to axis b, such that as shaft  20  is rotated about axis b, an axis a of interior section  29  orbits circularly about axis b. Similarly, end sections  32 ,  34  are each concentrically rotatably coupled to the support structures at an axis b′ and interior section  33  is mounted eccentrically with respect to axis b′, such that as shaft  22  is rotated about axis b′, an axis a′ of interior section  33  orbits circularly about axis b′. As a result of the connection between links  16 ,  18  and shafts  20 ,  22 , links  16 ,  18  are also rotated in a circular orbit such that an axis d moves in the same manner as axes a, a′. Nip roll body  26  is eccentrically mounted with respect to axis d and a distance between axis d and a center axis C, which represents a geometric center of nip roll body  26  (i.e., center axis C is equidistant from an outer diameter of nip roll body  26 ), is equal to both a distance between axis a and axis b and a distance between axis a′ and axis b′. Nip roll  14  is driven by a nip roll input shaft  36 , which is coincident with axis d, at an angular velocity magnitude that is equal to an angular magnitude at which eccentric shafts  20 ,  22  are driven about respective axes b, b′, but in the opposite direction. Input shaft  36  is rotatably coupled to both links  16 ,  18 . A drive of nip roll  14  is configured to accommodate the orbital translation of axis d, and for example, may include a 3-plane Schmidt coupling and be configured similar to a drive arrangement  200  shown in  FIG. 6 . 
     During one complete revolution of nip roll  14  about axis d, which coincides with one complete revolution of eccentric shaft  20  about axis a and one complete revolution of eccentric shaft  22  about axis a′, a linear velocity variation of the outer surface of nip segment  24  has a course represented by one complete sinusoidal curve, which has a maximum value and a minimum value. Depending on the phasing of nip roll  14 , nip segment  24  may first contact passing signature  12  ( FIG. 1 ) when the velocity of the outer surface of nip segment  24  is at a maximum value and then decelerate signature  12  ( FIG. 1 ) as the velocity of the outer surface of nip segment  24  approaches the minimum value. Alternatively, nip segment  24  may first contact passing signature  12  ( FIG. 1 ) when the velocity of the outer surface of nip segment  24  is at a minimum value and then accelerate signature  12  ( FIG. 1 ) as the velocity of the outer surface of nip segment  24  approaches the maximum value. 
       FIGS. 3   a  to  3   c  schematically show upper section  11  of signature velocity changing apparatus  10  contacting and decelerating signature  12 . Lower section  13  ( FIG. 1 ) operates opposite of signature  12  from upper section  11  in a manner that is a mirror image of upper section  11  for decelerating signature  12 . In  FIGS. 3   a  to  3   c , nip roll  14  is rotated in one direction, i.e., counterclockwise, by shaft  36  ( FIG. 2 ) at an angular velocity magnitude ω, while eccentric shafts  20 ,  22  are rotated in the opposite direction, i.e., clockwise, at the same angular velocity magnitude ω. Eccentric shafts  20 ,  22  and nip roll  14  also have the same eccentricity Xecc. A phasing between eccentric shafts  20 ,  22  and nip roll  14  is set so that a velocity Vn of nip segment  24  in the X-direction at nip  31  is at a maximum value in  FIG. 3   a  and at a minimum value in  FIG. 3   c . The phasing also maintains a constant nip elevation at the point of contact of nip segment  24  with signature  12  as nip segment  24  passes nip  31 , such that vertical motions of the two eccentric components, nip roll  14  and eccentric shafts  20 ,  22 , cancel each other out. As a result, center axis C is not translated in the vertical direction as signature  12  is decelerated. 
       FIG. 3   a  shows upper section  11  as nip segment  24  comes into contact with signature  12 . Axes a, a′ are directly above respective axes b, b′ and axis d is directly above center axis C. In the position shown in  FIG. 3   a , eccentric shafts  20 ,  22  are translating axes a, a′, d in the X-direction at a velocity Va that is equal to an angular velocity magnitude ω of shafts  20 ,  22  multiplied by an eccentricity Xecc of eccentric shafts  20 ,  22  (Va=ω*Xecc). Meanwhile, nip roll  14  is also being rotated by shaft  36  ( FIG. 2 ) about axis d at angular velocity magnitude ω so that center axis C, relative to axis d, is translating in the X-direction at a velocity Vca equal to angular velocity magnitude ω of shaft  36  ( FIG. 2 ) multiplied by eccentricity Xecc of nip roll  14  (Vca=ω*Xecc). A net velocity Vc of center axis C in the X-direction is equal to velocity Va of axes a, a′, d plus velocity Vca of center axis C relative to axis d, which equals two multiplied by angular velocity magnitude ω multiplied by eccentricity Xecc (Vc=Va+Vca=2*ω*Xecc). A velocity Vn of nip segment  24  in the X-direction at nip  31  is then equal to a radius R of nip roll  14  multiplied by angular velocity magnitude ω of nip roll  14  plus net velocity Vc of center axis C (Vn=R*w+2*ω*Xecc). 
       FIG. 3   b  shows upper section  11  in the middle of decelerating signature  12 . From  FIG. 3   a  to  FIG. 3   b , nip roll  14  is rotated ninety degrees counterclockwise about axis d and eccentric shafts  20 ,  22 , and respective axes a, a′, are rotated ninety degrees clockwise about respective axes b, b′. Axis d is rotated ninety degrees clockwise in a circular orbit by eccentric shafts  20 ,  22  while center axis C is rotated ninety degrees counter clockwise about axis d by shaft  36  ( FIG. 2 ). In the position shown in  FIG. 3   b , axes a, a′, d are only translating downwardly, not in the X-direction, and center axis C is only translating upwardly with respect to axis d, not in the X-direction. As a result, net velocity Vc of center axis C is zero in the X-direction and velocity Vn of nip segment  24  at nip  31  is equal to radius R of nip roll  14  multiplied by angular velocity magnitude ω of nip roll  14  (Vn=R*ω). 
       FIG. 3   c  shows upper section  11  at the end of decelerating signature  12 , with nip segment  24  releasing signature  12 . From  FIG. 3   b  to  FIG. 3   c , nip roll  14  is rotated ninety degrees counterclockwise about axis d and eccentric shafts  20 ,  22  and respective axes a, a′ are rotated ninety degrees clockwise about respective axes b, b′. In the position shown in  FIG. 3   c , eccentric shafts  20 ,  22  are translating axes a, a′, d away from the X-direction, such that a velocity Va is a negative value equal to an angular velocity magnitude ω of shafts  20 ,  22  multiplied by an eccentricity Xecc of eccentric shafts  20 ,  22  (Va=−ω*Xecc). Meanwhile, nip roll  14  is also being rotated by shaft  36  ( FIG. 2 ) about axis d at angular velocity magnitude ω so that center axis C is translating away from the X-direction, such that a velocity Vca of center axis C relative to axis d is a negative value equal to angular velocity magnitude ω of shaft  36  ( FIG. 2 ) multiplied by eccentricity Xecc of nip roll  14  (Vca=−ω*Xecc). A net velocity Vc of center axis C in the X-direction is a negative value is equal to velocity Va of axes a, a′, d plus velocity Vca of center axis C relative to axis d, which equals two multiplied by angular velocity magnitude ω multiplied by eccentricity Xecc (Vc=Va+Vca=−2*ω*Xecc). A velocity Vn of nip segment  24  in the X-direction at nip  31  is then at a minimum value that is equal to radius R of nip roll  14  multiplied by angular velocity magnitude ω of nip roll  14  plus net velocity Vc of center axis C, which is a negative value (Vn=R*ω−2*ω*Xecc). 
       FIGS. 4   a  to  4   c  schematically show upper section  11  of signature velocity changing apparatus  10  contacting and accelerating signature  12 . Lower section  13  ( FIG. 1 ) operates opposite of signature  12  from upper section  11  in a manner that is a mirror image of upper section  11  for accelerating signature  12 . In  FIGS. 4   a  to  4   c , nip roll  14  is rotated counterclockwise, while eccentric shafts  20 ,  22  are rotated clockwise. A phasing between eccentric shafts  20 ,  22  and nip roll  14  is set so that a velocity Vn of nip segment  24  in the X-direction at nip  31  is at a minimum value in  FIG. 4   a  and at a maximum value in  FIG. 4   c . During the acceleration of signature  12 , similar to the deceleration of signature shown in  FIGS. 3   a  to  3   c , the phasing also maintains a constant nip elevation at the point of contact of nip segment  24  with signature  12  as nip segment  24  passes nip  31 , such that vertical motions of the two eccentric components, nip roll  14  and eccentric shafts  20 ,  22 , cancel each other out. As a result, center axis C is not translated in the vertical direction as signature  12  is accelerated. 
       FIG. 4   a  shows upper section  11  just as nip segment  24  comes into contact with signature  12 . Axes a, a′ are directly below respective axes b, b′ and axis d is directly below center axis C. In the position shown in  FIG. 4   a , eccentric shafts  20 ,  22  are translating axes a, a′, d away from the X-direction, such that a velocity Va is a negative value equal to an angular velocity magnitude ω of shafts  20 ,  22  multiplied by eccentricity Xecc of eccentric shafts  20 ,  22  (Va=−ω*Xecc). Meanwhile, nip roll  14  is also being rotated by shaft  36  ( FIG. 2 ) about axis d at angular velocity magnitude ω so that center axis C is translating away from the X-direction. Center axis C is translating relative to axis d at velocity Vca that is a negative value equal to angular velocity magnitude ω of shaft  36  ( FIG. 2 ) multiplied by eccentricity Xecc of nip roll  14  (Vca=−ω*Xecc). Net velocity Vc of center axis C in the X-direction is a negative value equal to velocity Va of axes a, a′, d plus velocity Vca of center axis C relative to axis d, which equals two multiplied by angular velocity magnitude ω multiplied by eccentricity Xecc (Vc=Va+Vca=−2*ω*Xecc). A velocity Vn of nip segment  24  in the X-direction at nip  31  is then at a minimum value that is equal to radius R of nip roll  14  multiplied by angular velocity magnitude ω of nip roll  14  plus net velocity Vc of center axis C, which is a negative value (Vn=R*ω−2*ω*Xecc). 
       FIG. 4   b  shows upper section  11  in the middle of accelerating signature  12 . From  FIG. 4   a  to  FIG. 4   b , nip roll  14  is rotated ninety degrees counterclockwise about axis d and eccentric shafts  20 ,  22 , and respective axes a, a′, are rotated ninety degrees clockwise about respective axes b, b′. Axis d is rotated ninety degrees clockwise in a circular orbit by eccentric shafts  20 ,  22  while center axis C is rotated ninety degrees counter clockwise about axis d by shaft  36  ( FIG. 2 ). In the position shown in  FIG. 4   b , axes a, a′, d are only translating downwardly, not in the X-direction, and center axis C is only translating upwardly with respect to axis d, not in the X-direction. As a result, net velocity Vc of center axis C is zero in the X-direction and velocity Vn of nip segment  24  at nip  31  is equal to radius R of nip roll  14  multiplied by angular velocity magnitude ω of nip roll  14  (Vn=R*ω). 
       FIG. 4   c  shows upper section  11  at the end of accelerating signature  12 , with nip segment  24  releasing signature  12 . From  FIG. 4   b  to  FIG. 4   c , nip roll  14  is rotated ninety degrees counterclockwise about axis d and eccentric shafts  20 ,  22 , and respective axes a, a′, are rotated ninety degrees clockwise about respective axes b, b′. In the position shown in  FIG. 4   c , eccentric shafts  20 ,  22  are translating axes a, a′, d in the X-direction at a velocity Va that is equal to an angular velocity magnitude ω of shafts  20 ,  22  multiplied by an eccentricity Xecc of eccentric shafts  20 ,  22  (Va=ω*Xecc). Meanwhile, nip roll  14  is also being rotated by shaft  36  ( FIG. 2 ) about axis d at angular velocity magnitude ω so that center axis C is translating in the X-direction with respect to axis d at a velocity Vca that is equal to angular velocity magnitude ω of shaft  36  ( FIG. 2 ) multiplied by eccentricity Xecc of nip roll  14  (Vca=ω*Xecc). Net velocity Vc of center axis C in the X-direction is equal to velocity Va of axes a, a′, d plus velocity Vca of center axis C relative to axis d, which equals two multiplied by angular velocity magnitude ω multiplied by eccentricity Xecc (Vc=Va+Vca=2*ω*Xecc). A velocity Vn of nip segment  24  in the X-direction at nip  31  is then equal to a radius R of nip roll  14  multiplied by angular velocity magnitude ω of nip roll  14  plus net velocity Vc of center axis C (Vn=R*ω+ 2 *ω*Xecc). 
       FIG. 5  shows an upper section  111  of a signature velocity changing apparatus according to another embodiment of the present invention. Upper section  111  includes eccentric shafts  20 ,  22  and links  16 ,  18  that are configured in the same manner as in  FIGS. 1 to 4   c , with axes a, a′ circularly orbiting respective axes b, b′ during operation. Upper section  111  also includes a nip roll  114  that includes a nip roll body  126  and nip segments  124  for contacting signatures. Nip roll  114  is driven by a shaft  136  about an axis d′. Shaft  136  is rotatably coupled to links  16 ,  18 , so shaft  136  can rotate about axis d′ as eccentric shafts  20 ,  22  cause shaft  136  to rotate in a circular orbit. Roll body  126  is concentrically mounted on shaft  136  about axis d′. Nip segments  124  are contoured to correspond to the eccentric movement that is translated to nip roll  114  via links  16 ,  18 . Nip segments  124  have a varying thickness, such that even though roll body  126  is concentrically mounted, nip segments can maintain contact with and accelerate or decelerate signatures that enter a nip formed between upper section  111  and a corresponding lower section that is configured similar to upper section  111 , in mirror image. 
       FIG. 6  shows a drive arrangement  200  for driving upper section  111  according to an embodiment of the present invention. A gear  202  drives external eccentric shaft  20  so that axis a of interior section  29  orbits about axis b. A gear  204  intermeshed with gear  202  is also driven by gear  202 . Gear  204  drives roll body  126  about axis d′. A gear  206  intermeshed with gear  204  is also driven by gear  204 . Gear  206  drives external eccentric shaft  22  so that axis a′ of interior section  33  orbits about axis b′. Gears  202 ,  204 ,  206  all have stationary centers and have a common diameter, with gears  202  and  206  rotating in one direction and gear  204  in an opposite direction. A Schmidt coupling  208  is employed between gear  204  and shaft  136  to drive nip roll  114  about axis d′. Schmidt coupling  208  allows gear  204  to rotate shaft  136  as shaft  136  is translated in a circular orbit by links  16  ( FIG. 5 ),  18 . Nip segments  124  transport signatures in a direction D. In an alternative embodiment, a ring and sun gear arrangement may be used in place of Schmidt coupling  208 . Drive arrangement  200  may also be used to drive upper section  11  shown in  FIGS. 1 to 4   c.    
     In the disclosed embodiments of the signature velocity changing apparatus, eccentric shafts  20 ,  22  are located external of nip rolls  14 ,  15 ,  114 , where there is more space and less geometric constraints. Less geometric constraints may advantageously allow the disclosed embodiments to be used to accelerate and decelerate signature of small cutoffs. The disclosed embodiments may advantageously provide increased durability and decreased cost, where off-the-shelf components can be 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.