Method and apparatus for half folding paper sheets

Method and apparatus for half folding sequentially and nesting a plurality of paper sheets. The apparatus includes a buckle chute folder, the folder having a first pair of feed rollers rotatable at a given velocity, and a device for continuously feeding the paper sheets in shingled relationship at a second velocity greater than the given velocity to the feed rollers. The shingled relationship is defined by an overlap of the sheets of at least one-half of the length of the sheets. By using the apparatus and method, any desired number of sheets may be folded sequentially and nested one inside the other.

BACKGROUND OF THE INVENTION 
The instant invention relates to folding sheets of paper with buckle 
chutes, and more particularly to sequential folding in half by a buckle 
chute of a plurality of sheets of paper and the subsequent nesting of the 
folded sheets of paper into a packet and the insertion of the packet into 
an envelope. 
There presently exists a need in the area of folding of paper sheets by 
means of buckle chute folders to be able to fold together a relatively 
large number, such as 10, 20, 30 or more, or paper sheets or documents. 
This requirement comes about by virtue of businesses, such as utilities or 
banks or retail stores, having large statements or bills which in many 
cases may exceed 30 more sheets of paper, most or all of which may need to 
be folded in order to be inserted into an envelope for mailing to a 
customer. Typically, the feeding of the sheets of paper, the folding of 
the sheets of paper, and the insertion of the folded sheets of paper into 
the envelope are effected by an inserting system comprising documents 
feeders, conveyors, buckle chute folders and envelope feeders. 
A critical limitation with the aforesaid state of the art inserting system 
is the inability to fold a large number of sheets together simultaneously, 
in large part due to the high speed of these systems. Some of the most 
critical limitations are the noise of the sheets of paper entering and 
leaving the folding rollers and the tremendous force required to maintain 
pressure of the folding rollers relative to each other as they separate to 
accept a large number of sheets together. 
It is therefor extremely desirable to have a practical solution to the 
foregoing problem of folding a large number of sheets simultaneously. The 
instant invention provides such a solution by providing apparatus and a 
method for half-folding a plurality of paper sheets sequentially and 
subsequently nesting the half-folded sheets and thereby attaining a result 
which in terms of quality of fold is superior to simultaneous folding of 
the same large number of sheets. 
SUMMARY OF THE INVENTION 
The instant invention accordingly provides apparatus and a method for 
half-folding sequentially and nesting a plurality of paper sheets. The 
apparatus includes a buckle chute folder, the folder having a first pair 
of feed rollers rotatable at a given velocity, and means for continuously 
feeding the paper sheets in shingled relationship at a velocity greater 
than the given velocity to the feed rollers. The shingled relationship is 
defined by an overlap of the sheets of about one quarter but less than one 
half of the length of the sheets, whereby any desired number of sheets may 
be folded sequentially and nested one inside the other.

DETAILED DESCRIPTION 
In describing the preferred embodiment of the instant invention, reference 
is made to the drawings wherein there is seen in FIGS. 1-3 a 
conveyor-accumulator 10 consisting of three upper belts 12, 14 and 16 
mounted on driven pulleys 18, 20 and 22 respectively and on idler pulleys 
24, 26 and 28 respectively. The driven pulleys 18, 20 and 22 are fixedly 
mounted on a drive shaft 30 which is driven by a motor (not shown). The 
idler pulleys 24, 26 and 28 are rotatably mounted on a shaft 32 journalled 
in the frame (not shown) of the conveyor-accumulator 10. The 
conveyor-accumulator 10 typically is part of a total folding and inserting 
system. 
The conveyor-accumulator 10 further includes immediately below the upper 
belts 12, 14 and 16 a pair of lower belts 34 and 36 mounted on driven 
pulleys 38 and 40 respectively and on idler pulleys 42 and 44 
respectively. The belts 12, 14, 16, 34 and 36 are preferably "0" ring 
belts. The driven pulleys 38 and 40 are fixedly mounted on a drive shaft 
46 which is driven by a motor (not shown) and the idler pulleys 42 and 44 
are rotatably mounted on a shaft 48. As best seen in FIG. 3, the upper 
reaches 50 and 52 of the lower belts 34 and 36 respectively are situated 
immediately below the lower reaches 54, 56 and 58 of the upper belts 12, 
14 and 16 respectively. As best seen in FIG. 2, a plan view, the lower 
belt 34 is situated between the upper belts 12 and 14 and the lower belt 
36 is situated between the upper belts 14 and 16. 
Three sheet elevating ramps 60, 62 and 64 are rigidly suspended below the 
lower reaches 54, 56 and 58 of the upper belts 12, 14 and 16 respectively 
along a conveying path moving in the direction of the arrows seen in FIGS. 
1-3. The functioning of the ramps 60, 62 and 64 and of the entire 
conveyor-accumulator 10 will be explained in additional detail 
hereinbelow. 
Located downstream of the accumulator-conveyor 10 is a conventional buckle 
chute folder generally designated 66 consisting of a first pair of feed 
rollers 68 and 70 and a third feed roller 72 which cooperates with the 
roller 70 to form a second pair of feed rollers. The buckle chute folder 
66 also includes a conventional buckle chute 74 having a stopping bar 76 
therein (see FIGS. 4-6). 
In operation, the conveyor-accumulator 10 feeds seriatim a stream of sheets 
78 which have been separated from a stack (not shown) of sheets upstream 
by a singulating device (not shown) between the lower reaches 54, 56 and 
58 of the upper belts 12, 14 and 16 respectively and the upper reaches 50 
and 52 of the lower belts 34 and 36 respectively at a desired velocity 
consistent with the overall folding and inserting system of which the 
conveyor-accumulator 10 is a component. The sheets 78, as they are fed 
seriatim by the conveyor-accumulator 10, encounter the three sheet 
elevating ramps 60, 62 and 64 whose upstream portions intercept the 
leading end 80 of the sheet 78 (see FIG. 1) to thereby cause the sheets 78 
to become slightly elevated. This slight elevation results in each sheet 
78 being deposited upon the preceding sheet 78 downstream of the ramps 60, 
62 and 64 and upstream of the feed rollers 68 and 70 which function 
similar to a registration device in that their slow speed results in the 
sheets 78 being slowed considerably after leaving the conveyor-accumulator 
10. The buckle chute folder 66 has its stopping bar 76 positioned so that 
the sheets 78 are folded in half, and in order to achieve this half fold, 
it is necessary that the sheets 78 have a shingled relationship to each 
other prior to entering the feed rollers 68 and 70. A shingled 
relationship is defined to mean a plurality of sheets whose leading or 
downstream ends are offset from on another, so that their leading or 
downstream ends are not aligned to form a vertical plane. It has been 
found that in creating the half fold, a shingled relationship in which the 
overlap of one sheet to the adjacent sheet is at least one half of the 
length of the sheet is required. Achieving this overlap is effected by 
having the sheets 78 moved through feed rollers 68 and 70 at a speed 
between about 5 to 40% that of the speed the sheets 78 are moved by the 
conveyor-accumulator 10, the preferred range being between about 10 and 
20%. For example, if the accumulator-conveyor 10 is moving the sheets 78 
at the speed of 100 inches per second, then the rollers 68 and 70 should 
move the sheets 78 at a speed of about 5 to 40 inches per second 
(preferably between about 10 to 20 inches per second) to produce 
overlapping of the sheets prior to their entry into the nip of the rollers 
68 and 70 of between about three quarters and one half of their length. It 
should be noted that sufficient shingling can be effected by almost any 
differences in speed between the conveyor-accumulator 10 and the roller 68 
and 70; e.g. a 1% difference in speed can work although such a small 
differential may not be commercially feasible. 
The result of the sheets 78 being shingled as described above prior to 
entry into the nip of the feed rollers 68 and 70 is illustrated in FIGS. 
4-7. The pressure of the feed rollers 68 and 70 feeds the sheets 78 into 
the buckle chute 66 toward the stopping bar 76. As the leading edge 80a of 
the sheet 78a is stopped by the buckle chute stopping bar 76, as seen in 
FIG. 4, a buckle 82 is formed in the middle of the sheet 78a towards the 
nip of the rollers 70 and 72. The succeeding sheets 78b, 78c, 78d, etc. 
continue to enter the buckle chute 66 and are not affected by the buckling 
and folding of the sheet 78a. 
As seen in FIG. 5, continued feeding of the sheet 78a by the roller pair 70 
and 72 causes a fold 84 to be formed in the location of the buckle 82 once 
the buckle area 82 exits the nip of the rollers 70 and 72. Simultaneously, 
as seen in FIG. 5, a buckle 86 is being formed in the succeeding sheet 78b 
so that sheet 78b is being folded inside preceding sheet 78a as the sheet 
78a exits the rollers 70 and 72. As clearly seen in FIGS. 4-7, only one 
sheet at a time is being folded, and as best seen in FIG. 6, after the 
sheets 78 exit the rollers 70 and 72 they nest inside one another, as they 
enter a guide platform 88 which holds the nested packet of sheets 78, 
which in the case seen in the drawings, consists of four sheets 78 a-d. As 
seen in FIG. 7, once the four sheets 78 a-d have exited the nip of the 
rollers 70 and 72, all of the four sheets 78 a-d rest against the platform 
88 remote from the rollers 70 and 72. 
Once the sheets 78 a-d are accumulated on the platform 88, they are removed 
by conventional means and may be inserted into an envelope (not shown). It 
can be appreciated that there is virtually no limit to the number of 
sheets 78 which may be folded and nested inside each other, but there is a 
practical limitation imposed by the thickness of the envelope. 
Although the invention has been described in conjunction with the foregoing 
specific embodiment, many alternatives, variations and modifications will 
be apparent to those of ordinarily skill in the art. Those alternatives, 
variations and modifications are intended to fall within the spirit and 
scope of the appended claims.