Apparatus for stacking and delivering paper napkins, paper towels, and the like

A stacking and delivery apparatus for stacks of products such as paper napkins and paper towels includes a magazine into which the products are delivered to form stacks and which supports the stack along a path of product movement. A plurality of fingers are mounted on a conveyor adjacent the magazine, and the conveyor moves a finger into the path of stack movement when a stack is completed and separates the completed stack from the next stack. A drive system for the conveyor moves the conveyor at different speeds during each cycle in which a stack is formed--a first, fast speed at which a finger is quickly moved into the path after a stack is completed, a second, relatively slow speed at which the finger moves the completed stack along the path as the next stack is built up behind the finger, a third, relatively fast speed at which the finger moves the completed stack rapidly along the path, and a fourth speed, which can be zero, during which a completed stack is removed from the conveyor.

BACKGROUND 
This invention relates to a stacking and delivery apparatus, and, more 
particularly, to a stacking and delivery apparatus for stacks of products 
such as paper napkins, paper towels, and the like. 
Paper napkins, paper towels, and similar products are automatically folded 
and delivered by well-known and conventional machines For example, Paper 
Converting Machine Company of Green Bay, Wisc. manufacturers machines 
known as the Super 6 and the Series 11 for cutting, folding, and 
delivering paper napkins. 
It is desirable to provide a machine for automatically dividing the product 
into stacks of a specified count and for delivering individual stacks for 
subsequent handling, such as packaging. U.S. Pat. No. 3,866,905 describes 
one type of automatic stacking and delivery apparatus. In this machine, 
separating or count fingers are inserted between individual products when 
a stack has been completed, and separate transfer fingers then engage the 
completed stack and move the stack toward the delivery end of the machine. 
However, the separate count fingers and transfer fingers require rather 
complex actuating means for moving the fingers at the appropriate times. 
SUMMARY OF THE INVENTION 
The invention provides an automatic stacking and delivery machine which 
uses a single set of fingers for both separating a completed stack and for 
transporting the completed stack. The fingers are mounted on a conveyor 
which extends along the path of movement of the stacks, and a drive system 
for the conveyor moves the conveyor and the fingers at several different 
velocities during each cycle in which a stack is formed. A finger is moved 
rapidly into the path when a stack has been completed to separate the 
completed stack from the next stack. The finger is then advanced 
relatively slowly as the next stack is built up behind the finger. When 
the next stack has been built up enough to be self-supporting, the finger 
is advanced rapidly to move the completed stack to a delivery point. The 
movement of the finger is then stopped to permit the stack to be removed. 
A single system controls both count separation and stack transport, and a 
single cam controls the system. A wide range of counts can be provided 
merely by changing the single cam.

DESCRIPTION OF SPECIFIC EMBODIMENTS 
Referring to FIG. 1, a conventional napkin converting machine 10 folds and 
delivers paper napkins to a stacking and delivery machine 11. A paper web 
W is supplied from a parent roll 12, passes over longitudinal folding 
plates 13 and through a nip roll set 14, 15, and is laid on the surface of 
a rotating anvil and vacuum carrier roll 16 which works in conjunction 
with a cutoff roll 17. 
Web segments are cut by the cutoff roll 17 to form individual napkins N 
which are folded in half by the vacuumized co-acting relationship between 
the vacuum roll 16 and a folding roll 18. A plurality of belts 19 are 
entrained around the folding roll 18 in axially spaced grooves therein and 
strip the folded napkins from the folding roll and deliver them downwardly 
to a delivery position where they are subsequently packed out by an 
orbital packer 20. Without the automatic stacking and delivery machine, 
napkins would normally be delivered in continuous superposed relationship 
along a magazine 22 for manual count separation and transfer to packaging 
equipment. 
The foregoing napkin folding machine 10 and variations thereof, as well as 
different style packers, are well-known and well-defined in the prior art. 
The particular napkin folding machine illustrated is a Series 11 machine 
available from Paper Converting Machine Company. 
The stacking and delivery machine 11 includes a frame having a pair of 
spaced-apart side walls 24 and 25 (see also FIG. 2). The magazine 22 is 
mounted at the top of the side walls and includes a plurality of elongated 
bottom plates 26 (see also FIG. 11) which are horizontally spaced apart 
between the side walls and a plurality of elongated, vertically spaced 
side plates 27 on each side of the magazine. The magazine supports the 
napkins for movement along a horizontal path away from the orbital packer 
20. 
A pair of front sprockets 29 are keyed to a shaft 30 which extends between 
the frame side walls, and a pair of rear sprockets 31 are keyed to a shaft 
32. The sprockets are aligned with spaces between the bottom plates 26 of 
the magazine, and a chain 33 extends around each pair of longitudinally 
aligned front and rear sprockets 29 and 31. A plurality of fingers 35 are 
mounted on each chain, and the fingers on each chain extend upwardly 
through a space between a pair of bottom plates when the fingers are 
located on the top run of the chain which extends horizontally below the 
magazine (see FIG. 11). 
The drive system for the conveyor chains 33 is illustrated in FIG. 2, which 
shows the side opposite to that of FIG. 1. A sprocket 37 is keyed to the 
rear sprocket shaft 32 outside of the side wall 25 of the frame. A driYe 
sprocket 38 is mounted on a drive shaft 39 which is driven at constant 
speed by external drive means (not shown) such as a motor, gear connection 
to the converting machine 10, or the like. A pair of idler sprockets 41 
and 42 are mounted on pivotable lever arms 43 and 44, respectively. The 
lever arm 43 pivots on pin 45, and the lever arm 44 pivots on pin 46. A 
chain 47 wraps around the drive sprocket 38, the idler sprocket 42, the 
sprocket 37, and the idler sprocket 41. 
A control cam 49 is rotatably mounted on a shaft 50 and rotates 
continuously, making one revolution for each count cycle. The outer 
periphery 51 of the cam provides a camming surface which is engaged by a 
cam follower 52. The cam follower is mounted on a link 53 which is secured 
to a link 54, and both links are pivotally mounted on the frame by pin 55. 
A link 56 connects the upper end of link 54 to the lever arm 43 for the 
idler sprocket 41. Both of the movable sprockets 41 and 42 are located on 
one side of a line which extends between the sprocket 37 and the drive 
sprocket 39. 
As the cam follower 52 follows the contour of the camming surface, the 
links 53, 54, and 56 move the sprocket 41 toward or away from the sprocket 
42. Since the length of the chain 47 is fixed, as the sprocket 41 moves to 
the right in FIG. 2, the sprocket 42 is pulled to the left. The limit 
position of sprockets 41 and 42 are shown in phantom in FIG. 2 at 41' and 
42'. The lever arms 43 and 44 for the sprockets are connected to air 
cylinders 58 and 59, respectively, which bias the lever arms and in effect 
act as spring take-ups. Accordingly, as the cam follower moves radially 
inwardly on the cam, the sprocket 41 moves to the left in FIG. 2 and the 
sprocket 42 moves to the right. 
The keyed drive sprocket 38 is rotated continuously at constant speed in 
the direction indicated by the arrow. However, the idling sprocket 37 
which drives the shaft 32 and thus the two conveyor chains 33 can rotate 
at different speeds depending upon the movement of the sprockets 41 and 
42. When the cam follower 52 engages a portion of the cam which has a 
constant radius, the cam follower and the sprockets 41 and 42 do not move. 
The chain 33 is therefore driven at a constant speed by the drive sprocket 
38. When the radius of the cam increases, the cam follower and the 
sprocket 41 move to the right, and the chain 47 is pulled around the 
sprocket 37 at a faster rate, thereby increasing the speed of the conveyer 
chain 33. When the radius of the cam decreases, the cam follower 52 moves 
to the left, and the sprockets 41 and 42 move away from each other. The 
chain 47 then travels around the sprocket 37 at a slower rate, and the 
conveyor chain 33 slows down. The sprockets 41 and 42 therefore add to or 
substract from the constant velocity of the chain 47 which is provided at 
the drive sprocket 38, depending upon the contour of the cam. 
In FIG. 1 a pair of fingers 35a has just been rotated by the two conveyor 
chains 33 around the sprockets 29 into a vertical position in the path of 
movement of the napkins N. As the fingers move past the belts 19, they 
strip the last napkin from the belts to complete a stack S.sub.1 on the 
magazine. The fingers 35a are thereby interjected between two consecutive 
napkins which are delivered by the belts 19, the last napkin of the 
completed stack and the first napkin of the next stack. The first napkin 
of the next stack and subsequent napkins are packed out by the 
reciprocating packers 20 behind the vertical fingers 35a. 
It is therefore desirable that the fingers 35a move rapidly into their 
vertical position so that the fingers can be interjected between two 
napkins without slowing down the delivery speed of the folding roll 18. 
Once the fingers move into the path of napkin movement, the velocity of 
the conveyor chains 33 and the fingers is slowed so that the fingers move 
forwardly at the same rate at which the napkins of the next stack are 
built up behind the fingers by the packers 20. The fingers thereby provide 
support against which the napkins of the next stack can be packed. When a 
sufficient number of napkins of the next stack are packed so that the 
partial stack is supported, the velocity of the conveyor chains and the 
fingers is increased so that the fingers 35a and the completed stack 
S.sub.1 in front of the fingers are moved rapidly down the magazine. In 
FIG. 1 the fingers 35b have moved the previous stack S.sub.2 toward the 
delivery end of the magazine. 
When a stack reaches the delivery point along the magazine, the conveyor 
chains 33 and fingers 35 stop and dwell for a discrete period of time to 
permit the stack to be transferred from the magazine for subsequent 
handling. FIG. 2 shows a conventional transfer device 62 which includes a 
bucket 63 which is positioned on the magazine 22 to receive a stack 
S.sub.3 which is being pushed by finger 35c. After the stack has been 
pushed into the bucket and the conveyor chain stops, the bucket is pivoted 
90.degree. to move the stack to the position indicated at S.sub.4. 
FIG. 4 is a timing chart which illustrates the different velocity segments 
of the conveyor chains 33 and fingers 35 during one cycle or revolution of 
the control cam 49. The horizontal axis of the chart represents time, and 
the vertical axis represents the distance which the pusher fingers 35 
move. In the embodiment represented by FIG. 4 the count or number of 
napkins in each stack is 300, and the pusher fingers 35 are spaced 20 
inches apart on the conveyor chain. 
Velocity segment 65 represents the relatively high velocity at which a 
finger is interjected between two consecutive napkins when a stack is 
completed on the magazine (finger 35a in FIG. 1). Interjection of a finger 
occurs directly after the last napkin that completes a predetermined 
count, which is 300 in the embodiment represented in FIG. 4. 
Subsequent napkins are delivered and packed behind the finger 35a, and the 
finger provides support against which the napkins can be packed. In order 
to provide space for subsequent napkins being packed, the conveyor chain 
and the fingers are moved forward at a different velocity segment 66 in 
FIG. 4. Velocity segment 66 corresponds to the rate at which napkins are 
packed by the packers 20 and continues until the quantity of napkins being 
stacked is sufficient to be held by stack-supporting devices on the 
magazine which will be described in detail hereinafter. 
Position 66a in FIG. 4 represents the position of the finger 35a at which 
the partial stack which is being packed behind the finger is properly 
supported. At this point the finger 35a has moved one inch from the 
position at which velocity segment 66 began. The velocity of the conveyor 
chain and the fingers is then increased as indicated at 67 to move the 
finger 35a and the completed stack S.sub.1 ahead of the finger 35a down 
the magazine. Forward motion of the conveyor chain and the fingers is 
stopped after the finger 35a has moved 17 inches during velocity segment 
67, and the fingers and the completed stacks dwell as indicated by the 
zero velocity segment 68. During the dwell period a completed stack can be 
transferred from the magazine, for example by the transfer device 62. 
After the dwell period, the conveyor chain moves at velocity 69 to move 
the next finger into position to be interjected between two consecutive 
napkins for count separation of the stack which is being packed on the 
magazine. 
It will be appreciated that when the partial stack which is being packed at 
the left end of the magazine in FIG. 1 becomes supported, the fingers move 
independently of the partial stack, and the packers 20 continue to pack 
the partial stack at a constant rate. The partial stack will not be 
contacted by the pusher fingers until the beginning 65 of the cycle 
represented in FIG. 4 when a pair of fingers is moved rapidly into the 
path of napkin movement to complete the count and separate the then 
completed stack from the next napkin. 
At least two sets of finger pairs 35 are required for the foregoing cycle. 
However, most embodiments will utilize four or five sets of fingers fo 
proper stack transport and spacing. 
The straight line 70 in FIG. 4 represents the constant velocity of the 
conveyor chain at the drive sprocket 38 which is rotated at a constant 
speed. The slopes of velocity segments 65 and 67 are greater than the 
slope of line 70, and during these segments the contour of the control cam 
49 which engages the cam follower 52 is such that it moves the movable 
sprockets 41 and 42 so that the chain 47 travels over sprocket 37 faster 
than it is driven by the drive sprocket 38. The slope of velocity segment 
66 is less than the slope of line 70, and during this segment the cam 
causes the chain 47 to travel over the sprocket 37 slower than it is 
driven by the drive sprocket 38. During velocity segment 68, the chain 47 
and the sprocket 37 are stationary. During the velocity segment 69, the 
radius of the cam portion which engages the cam follower is constant, and 
the chain 47 travels over the sprocket 37 at the same speed at which it is 
driven by the drive sprocket. 
FIG. 3 illustrates one embodiment of a control cam 49 for achieving the 
five different velocity segments represented by the timing chart of FIG. 
4. The periphery 51 of the cam includes five different camming portions 72 
through 76 which engage the cam follower during each revoluton of the cam. 
The end points of the camming portions are indicated by the radial lines 
77-81. The cam makes one revolution during the cycle represented in FIG. 
4. 
FIG. 5-7 illustrate the automatic stacking and delivery apparatus 11 
working in conjunction with a machine 84 having double the capacity of the 
converting machine 10 shown in FIG. 1. In FIGS. 5-7 a two-wide web W is 
split into individual strands W1 and W2, each of which pass sequentially 
through or over various devices such as longitudinal folding plate 85, nip 
rolls 86 and 87, cutoff roll 88, anvil/vacuum carrier roll 89, and folding 
roll 90. The napkins N are stripped from the folding rolls by belts 91 
which ride in grooves in the folding rolls, and the napkins move 
downwardly in superposed pairs between the belts 91 and a guide strip 92 
until they are positioned for pack out by packer fingers 93 which 
reciprocate about shaft 94. The machine 84 is a conventional Super 6 
machine available from Paper Converting Machine Company. 
In FIG. 5 a pair of pusher fingers 35a have been rotated by the sprocket 29 
to a vertical position in front of the delivery belts. In this position, a 
completed stack would be to the left of the fingers 35a and the next stack 
would be packed against the right side of fingers 35a. 
From position 35a to the position illustrated in phantom at 35d, the 
fingers 35a move at a velocity equal to the rate of stack build-up. A 
plurality of pivoted support plates 95 (see also FIG. 8) are urged against 
the vertical side edges of the napkin stack to help maintain the stack in 
an upright position and provide some resistance against the force of the 
packing fingers 93. In FIG. 8 the support plates 95 are supported by a 
piano hinge plate 96 which is attached to the side rails 27 on each side 
of the magazine. The plates are mounted on a hinge pin 96a and are 
resiliently biased toward the stack by springs 97. Each of the support 
plates can pivot into engagement with the stack between the side rails 27 
of the magazine. 
A plurality of S-curved support fingers 98 are suspended from rods 99 which 
are pivotally supported by brackets 100 on the sides of the magazine. Two 
or more support fingers are suspended from each rod. The support fingers 
contact the upper front portion of the stack as it is built up and moved 
down the magazine. 
Once the partial stack is built up to finger position 35d and is under the 
control of the side support plates 95 and the top support fingers 98, the 
pusher fingers and the completed stack in front of the pusher fingers can 
move rapidly forward to transport the completed stack out of the general 
proximity of the packer. This occurs during the previously described 
velocity segment 67 of FIG. 4, after which the completed stack will be 
stopped for subsequent transfer or handling during the dwell segment 68. 
FIG. 9 is a timing chart illustrating the velocity curves used for the 
napkin folding machine 84 of FIG. 5. For the machine illustrated in FIG. 1 
and the timing chart of FIG. 4, the total productivity is at least 600 
napkins per minute per lane. The productivity of the machine 84 is at 
least 1200 napkins per minute per lane. 
In FIG. 9 certain velocity segments are below and others are above the 
constant velocity base speed of the drive sprocket 38 which is represented 
by the straight line 104. This means that in the speed changing system of 
FIG. 2, the movable sprocket 41 will be moved in one direction by the 
control cam 49 when a given velocity segment is greater than the constant 
velocity base speed and will move in the other direction when the velocity 
segment is below the constant velocity base speed. 
During the first velocity segment 106, the conveyor chain and pusher 
fingers are moved rapidly to move one of the pairs of fingers behind a 
completed stack. The conveyor chain and pusher fingers then move at a 
slower velocity 107 as the next stack is built up. When the partial stack 
becomes self-supporting, the conveyor chain and pusher fingers move 
rapidly during velocity segment 108 to move the completed stack 
downstream. The completed stack is removed during the dwell segment 109, 
and the fingers thereafter are moved at velocity 110 to bring a finger 
into position for count separation. Count separation occurs at the 
beginning of the next cycle during velocity segment 106. 
The timing chart of FIG. 9 is for a 60 count stack. Since the napkin 
folding machine 84 delivers 1200 napkins per lane per minute to the 
stacking and delivery machine, the cycle for 60 count stacks is 20 stacks 
per minute or three seconds for each cycle. The time along the horizontal 
axis of FIG. 9 is therefore three seconds for the complete cycle. 
FIG. 10 is a timing chart similar to FIG. 9 for a 100 count stack. 
In the embodiment illustrated, each of the pusher fingers 35 is connected 
to the conveyor chain 33 by a pair of pins 112 (FIGS. 7 and 11) which 
connect the links of the chain. FIG. 11 illustrates one lane of a multiple 
lane stacking machine. The stacks of each lane are moved between the side 
plates 27 which are supported by vertical posts 113. Four chains 33 extend 
below each lane of the magazine, and the pusher fingers 35 are arranged in 
sets of four which are spaced transversely across the magazine. 
Although the specific embodiment of FIG. 2 uses chains 47 and sprockets 37, 
41, 38 and 42 for changing velocity of the pusher fingers, it will be 
understood that other drive means could be used, for example, belts and 
pulleys or the like. Accordingly, the terms "chain" and "sprocket" as used 
herein and in the following claims are meant to include equivalent devices 
such as belts and pulleys. 
While the particular velocity modifying mechanism which is described in the 
application includes a cam, cam follower, linkages, movable sprockets, 
etc., equivalent means can be utilized to accomplish the same function. 
For example, a servo motor can be programmed for different velocities 
during one count cycle. 
While in the foregoing specification a detailed description of specific 
embodiments of the invention was set forth for the purpose of 
illustration, it will be understood that many of the details herein given 
may be varied considerably by those skilled in the art without departing 
from the spirit and scope of the invention.