Abstract:
A method and device for improving the stacking efficiency in a sheet accumulation system using a continuous web cutter for cutting a web of material into sheets and a plurality of right angle turn-over modules for changing the direction of the sheets and causing overlapping between adjacent sheets. Different movement mechanisms are used to move the sheets with different moving speeds from the web cutter toward the right angle turn-over modules for increasing the overlapped amount.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to a sheet accumulating system and, more particularly, to a continuous web cutter for providing cut sheets and a right angle transport device for stacking the cut sheets. 
     BACKGROUND OF THE INVENTION 
     Continuous web cutters are known in the art. Typically, a continuous web cutter is used to cut a continuous web of material into cut sheets, provide the cut sheets to a sheet accumulator and then to an insertion station in a mass mailing inserting system. As shown in FIG. 1, a continuous web of material with sprocket holes on both side of the web is fed from a fan-fold stack into the web cutter, which has two moving belts with sprockets (or tractors with pins) to move the web toward a guillotine cutting module for cutting the web cross-wise into separate sheets. Perforations are provided on each side of the web so that the sprocket hole sections of the web can be removed from the sheets prior to moving the cut sheets to other components of the mailing inserting system. In particular, the continuous web cutter, as shown in FIG. 1, is used to feed two webs of material linked by a center perforation. As shown, a splitter is used to split the linked webs into two separate webs before the webs are simultaneously cut by the cutting module into two cut sheets. The sheets are moved toward a right angle transport device so that the sheets are moved in a different direction, overlapping each other. Right angle transport devices are well known. For example, in U.S. Pat. No. 5,664,772, Auerbach et al. disclose a right angle transport device having two or more sheet turn-over modules, wherein the turn-over modules are placed at 45 degrees in the path of two or more sheets moving in a side-by-side fashion so that these sheets are turned over while their moving direction is changed by 90 degrees. As such, the sheets are moving substantially along the same line, with one sheet leading another in an overlapping manner. The overlapped mount by the two sheets using this type of right angle transport device is determined by the difference between the length and the width of the sheets. If the difference between the length and the width of the sheets is small, the overlapping between the two cut sheets may cause a paper jam when the sheets are collated into a stack in the sheet accumulator. Furthermore, with a small overlapped amount, a longer stacking mechanism must be used to collate the overlapped sheets into the stack. If the sheets are square or the length of the sheet is smaller than the width, then there is no overlapping when the sheets emerge from the right angle transport device. 
     It is advantageous and desirable to provide a method and device to increase the overlapped amount of the cut sheets as they exit the right angle transport device. 
     SUMMARY OF THE INVENTION 
     It is the primary object of the present invention to increase the overlapped amount of cut sheets in a continuous web cutter and a right angle transport device so as to increase the collating efficiency of a sheet accumulator. Accordingly, the first aspect of the invention is a continuous web cutter for cutting a web of material into groups of cut sheets, wherein each group of cut sheets comprises at least a first sheet and a second sheet, and wherein the first and second sheets are moved in a side-by-side fashion from the web cutter toward a right angle transport device for causing the first and second sheets to turn over while their moving direction is changed from a first direction to a second direction substantially perpendicular to the first direction, with the first sheet leading the second sheet in an overlapping manner, with an overlapped amount along the second direction. The web cutter comprises a first movement mechanism for moving the first sheet toward the right angle transport device with a first moving speed, and a second movement mechanism for moving the second sheet toward the right angle transport device with a second moving speed greater than the first moving speed for increasing the overlapped amount. 
     The second aspect of the present invention is a method of stacking sheets in a sheet accumulating system, including a right angle transport device, to change moving direction of sheets from a first direction to a second direction substantially perpendicular to the first direction, and a continuous web cutter for cutting a web of material into groups of cut sheets, wherein each group of cut sheets comprises at least a first sheet and a second sheet, and wherein the first and second sheets are moved substantially in a parallel fashion along the first direction from the web cutter toward the right angle transport device for causing the first and second sheets to turn over and move along the second direction, with the first sheet leading the second sheet in an overlapping fashion having an overlapped amount along the second direction. The method comprises the steps of providing a first movement mechanism for moving the first sheet with a first moving speed, and providing a second movement mechanism for moving the second sheet with a second moving speed greater than the first moving speed for increasing the overlapped amount. 
     The third aspect of the present invention is a sheet accumulating system, which comprises a right angle transport device to change moving direction of sheets from a first direction to a second direction substantially perpendicular to the first direction; a continuous web cutter for cutting a web of material into groups of cut sheets, wherein each group of cut sheets comprises at least a first sheet and a second sheet, and wherein the first and second sheets are moved along the first direct from the web cutter toward the right angle transport device for causing the first and second sheet to turn over and move along the second direction with the first sheet leading the second sheet in an overlapping fashion having an overlapped amount in the second direction; a first movement mechanism for moving the first sheet with a first moving speed; and a second movement mechanism for moving the second sheet with a second moving speed greater than the first moving speed for increasing the overlapped amount. 
     The present invention will become apparent upon reading the description taken in conjunction with FIGS. 2 to  8 . 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a mass mailing inserting machine using a continuous web cutter to cut a web of material into separate sheets. 
     FIG. 2 is a diagrammatic representation showing the top view of the continuous web cutter, a right angle transport device and a sheet accumulator. 
     FIG. 3 a  is a diagrammatic representation showing the position of two sheets moving toward the right angle transport device at the same speed after being cut by the web cutter. 
     FIG. 3 b  is a diagrammatic representation showing the position of two sheets engaged with the right angle transport device. 
     FIG. 3 c  is a diagrammatic representation showing the position of two sheets further engaged with the right angle transport device. 
     FIG. 3 d  is a diagrammatic representation showing the overlapping of two sheets as they exit the right angle transport device. 
     FIG. 3 e  is a diagrammatic representation showing the two overlapped sheets, which have disengaged themselves from the right angle transport device. 
     FIG. 4 a  is a diagrammatic representation showing the position of two sheets moving toward the right angle transport device at different speeds after being cut by the web cutter. 
     FIG. 4 b  is a diagrammatic representation showing the different positions of the sheets as they are engaged with the right angle transport device. 
     FIG. 4 c  is a diagrammatic representation showing the different positions of the sheets as they are further engaged with the right angle transport device. 
     FIG. 4 d  is a diagrammatic representation showing the overlapping of the sheets as they exit the right angle transport device. 
     FIG. 4 e  is a diagrammatic representation showing the increased overlapped amount due to the different moving speeds of the sheets. 
     FIG. 5 a  is a diagrammatic representation showing the side view of the web cutter having a movement mechanism for moving the sheets toward the right angle transport device. 
     FIG. 5 b  is a diagrammatic representation showing the top view of the web cutter and part of the movement mechanism. 
     FIG. 6 a  is a diagrammatic representation showing a preferred embodiment of the movement mechanism, according to the present invention. 
     FIG. 6 b  is a diagrammatic representation showing a pulley system for moving one of the sheets toward the right angle transport device. 
     FIG. 6 c  is a diagrammatic representation showing a different pulley system for moving the other sheet toward the right angle transport device. 
     FIG. 7 is a diagrammatic representation showing a different embodiment of the movement mechanism, according to the present invention. 
     FIG. 8 a  is a diagrammatic representation showing more than two sheets may be moved toward a right angle transport device having three turn over modules. 
     FIG. 8 b  is a diagrammatic representation showing three overlapped sheets as they emerge from the right angle transport device. 
    
    
     DETAILED DESCRIPTION 
     Referring to FIG. 2, a sheet accumulating system  1  includes a continuous web cutter  10  for feeding two webs of material  22 ,  24  linked by a center perforation  26  so that the webs can be simultaneously cut into sheets  42 ,  44  by a cutting module  16 . The webs  22 ,  24  are also linked to side strips  28  by perforations  30 . The side strips  28  have a plurality of holes  32  for feeding into the web cutter  10  by sprockets or tractor pins  12 . As shown in FIG. 2, a splitter  14  is used to separate part of the connected webs  22 ,  24  before they are cut into separate sheets  42 ,  44 . The sheets  42 ,  44  are moved along a first direction  102  toward a right angle transport device  50  in a side-by-side fashion. The right angle transport device  50  has two sheet turn-over modules  52 ,  54  placed at  45  degrees in the path of the incoming sheets  42 ,  44  so that the sheets  42 ,  44  are turned over and moved along a second direction  104  toward a sheet accumulator  60  for collation. 
     Conventionally, sheets  42 ,  44  are moved at the same speed toward the sheet turnover modules  52 ,  54  along the first direction  102 , as shown in FIG. 3 a . The moving speed is represented by arrow  106 . The length of the sheets  42 ,  44  is denoted by the letter L and the width is denoted by the letter W. As shown in FIG. 3 b , part of the sheets  42 ,  44  are turned over by the turn-over modules  52 ,  54 , and the turned over sections are moved along the second direction  104 , which is substantially perpendicular to the first direction  102 . FIG. 3 c  shows that the sheets  42 ,  44  are further engaged with the turn-over modules  52 ,  54 . Because they are moved at the same speed, the sheets  42 ,  44  are turned over by the same amount. As the sheets  42 ,  44  emerge from the turn-over modules  52 ,  54 , they move substantially on the same line along the second direction  104  with the sheet  42  leading the sheet  44 , and they are partially overlapped by an amount S, as shown in FIG. 3 d . The overlapped amount S is substantially equal to the difference between L and W. When the sheets  42 ,  44  are completely disengaged from the turn-over modules  52 ,  54 , they are overlapped by the same amount S, as shown in FIG. 3 e , if they are not moved by another moving mechanism in a different way. 
     FIGS. 4 a - 4   e  illustrate the method of moving the sheets  42 ,  44 , according to the present invention. The sheets  42 ,  44  are moved toward the turn-over modules  52 ,  54  with different speeds. As shown in FIG. 4 a , the sheet  42  is moved at a first speed  112  and the sheet  44  is moved at a second speed  114 , which is greater than the first speed  112 . As a result, the sheet  44  is turned over faster than the sheet  42 , as shown in FIGS. 4 b  and  4   c . As the sheets  42 ,  44  emerge from the turn-over modules  52 ,  54 , they are overlapped with each other with an amount S′, which is greater than the difference between L and W, as shown in FIGS. 4 d  and  4   e . Thus, even with square sheets or sheets with L smaller than W, the right angle transport device  40  (FIG. 2) can still be used for sheet collation. It is understood that the overlapped amount S′ can be adjusted by adjusting the difference between the second speed  114  and the first speed  112 . 
     Referring to FIG. 5 a , the sheets  42 ,  44  are moved from the web cutter  10  to the right angle transport device  50  by a group of rollers collectively denoted by reference numeral  120  and a movement mechanism  130 . As shown in FIG. 5 b , the roller group  120  includes two sets of rollers: one set of idler rollers  122  for moving the sheet  42  and another set of idler rollers  124  for moving the sheet  44 . The rollers  122  and  124  can be mounted on a common shaft  126 , or on different shafts, if so desired. Furthermore, additional moving devices  72  and  74  may be used to move the sheets  42 ,  44  while they are engaged with the right angle transport device  10 . 
     FIG. 6 a  illustrates the preferred embodiment of the moving mechanism  130 , according to the present invention. As shown in FIG. 6 a , the movement mechanism  130  includes two sets of rollers  174  and  154 , corresponding to the idler rollers  122  and  124 . The rollers  154  are fixedly mounted on a shaft  152  and a shaft mount  158 . The rollers  174  are fixedly mounted on a shaft  172  and a shaft mount  178 . The rollers  154  are driven by a pulley system  140 , and the rollers  174  are driven by another pulley system  160 . Preferably, the pulley systems  140 , 160  are driven by a motor  132  via a pulley system  134  and a common shaft  136 . In order to achieve different driving speeds on rollers  154  and  174 , it is possible to apply different mechanical advantages on the pulley systems  140  and  160 . For example, different mechanical advantages can be achieved by using pulleys of different diameters. As shown in FIGS. 6 b  and  6   c , the pulley system  140  includes a pulley  142 , which is driven by a pulley  144  via a belt  146 , and the pulley system  160  includes a pulley  162 , which is driven by a pulley  164  via a belt  166 . The diameter differential between the pulleys  144  and  142  is greater than the diameter differential between the pulleys  164  and  162 . Because the pulleys  144  and  164  are driven by the same motor  132 , the larger diameter differential on the pulley system  140  causes the rollers  154  to turn faster than the rollers  174  (FIG. 6 a ). Accordingly, the sheet  44  is moved toward the sheet turn-over module  54  with a greater speed than the sheet  42  being moved toward the sheet turn-over module  52 . 
     Alternatively, separate motors can be used to move the sheets  42 ,  44 . As shown in FIG. 7, the rollers  154  are driven by a motor  182  via pulley systems  180 ,  184 , and the rollers  174  are driven by a different motor  192  via pulley systems  190 ,  194 . If the motor  182  is faster than the motor  192 , then the pulley systems  180 ,  190  can be identical, and the pulley systems  184 ,  194  can be identical. 
     The movement mechanism, as described in conjunction with FIGS. 5 a  to  6   c , uses different mechanical advantages in pulley systems to achieve different driving speeds to move the sheets  42 ,  44  in the web cutter  10 . It is understood by those skilled in the art that there are numerous ways to achieve different driving speeds. For example, instead of using pulley systems  140  and  160 , as shown in FIGS. 6 a  to  6   c , it is possible to use gear systems to achieve different driving speeds. Furthermore, it is possible to stack three or more sheets in a sheet accumulation system with an increased overlapped amount, as shown in FIGS. 8 a  and  8   b . As shown in FIG. 8 a , three separate sheets  42 ,  44 ,  46  are moved in a side-by-side fashion along the moving direction  102  toward three sheet turn-over modules  52 ,  54 ,  56 . With different moving speeds  112 , 114  and  116 , the sheets  42 ,  44 ,  46  can be caused to overlap with each other with an increased overlapped amount, as shown in FIG. 8 b.    
     Thus, although the invention has been described with respect to a preferred embodiment thereof, it will be understood by those skilled in the art that the foregoing and various other changes, omissions and deviations in the form and detail thereof may be made without departing from the spirit and scope of this invention.