U.S. patent application number 14/489160 was filed with the patent office on 2015-03-19 for pack alignment apparatus and methods using linear motor.
This patent application is currently assigned to C.G. Bretting Manufacturing Co., Inc.. The applicant listed for this patent is Andrew Kell Balduc, Ryan Jay Lunn, James R. Michler, Jeffrey Tom Petersen, Timm G. Retzloff. Invention is credited to Andrew Kell Balduc, Ryan Jay Lunn, James R. Michler, Jeffrey Tom Petersen, Timm G. Retzloff.
Application Number | 20150078876 14/489160 |
Document ID | / |
Family ID | 51627953 |
Filed Date | 2015-03-19 |
United States Patent
Application |
20150078876 |
Kind Code |
A1 |
Michler; James R. ; et
al. |
March 19, 2015 |
PACK ALIGNMENT APPARATUS AND METHODS USING LINEAR MOTOR
Abstract
A system for forming and wrapping a plurality of stacks of
sheet-like product is provided. The system includes a stack aligner
for squaring up leading and trailing ends of the stack as well as
sides of the stacks is provided. The stack aligner is also
configured for controlling the position of the stacks along the
stack travel path such that the stacks exit the stack aligner with
tight positional tolerances for being fed to the stack wrapping
arrangement.
Inventors: |
Michler; James R.; (Ashland,
WI) ; Petersen; Jeffrey Tom; (Ashland, WI) ;
Lunn; Ryan Jay; (Ashland, WI) ; Balduc; Andrew
Kell; (Ironwood, MI) ; Retzloff; Timm G.;
(Washburn, WI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Michler; James R.
Petersen; Jeffrey Tom
Lunn; Ryan Jay
Balduc; Andrew Kell
Retzloff; Timm G. |
Ashland
Ashland
Ashland
Ironwood
Washburn |
WI
WI
WI
MI
WI |
US
US
US
US
US |
|
|
Assignee: |
C.G. Bretting Manufacturing Co.,
Inc.
Ashland
WI
|
Family ID: |
51627953 |
Appl. No.: |
14/489160 |
Filed: |
September 17, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61879236 |
Sep 18, 2013 |
|
|
|
Current U.S.
Class: |
414/789.1 ;
414/802 |
Current CPC
Class: |
B65H 31/3081 20130101;
B65G 47/28 20130101; B65H 31/34 20130101; B65H 2701/182 20130101;
B65H 2555/134 20130101; B65G 54/02 20130101; B65H 5/006 20130101;
B65H 2404/731 20130101; B65H 2701/1924 20130101 |
Class at
Publication: |
414/789.1 ;
414/802 |
International
Class: |
B65H 31/34 20060101
B65H031/34 |
Claims
1. A method of aligning a stack of a plurality of vertically
stacked sheet-like products as the stack travels along a travel
path as the stack travels through a stack aligner along the travel
path, the stack having a downstream leading end, an upstream
trailing end, a pair of sides extending between the leading end and
the trailing end, a top and a bottom, the method comprising:
feeding the stack to the stack aligner, pressing the stack between
a first paddle of the stack aligner that is downstream from the
stack and a second paddle of the stack aligner that is upstream
from the stack so as to substantially align all of the sheet-like
product such that the leading end and trailing end of the stack are
substantially parallel to one another and orthogonal to the travel
path.
2. (canceled)
3. The method of claim 1, further comprising squeezing the stack in
a transverse direction that is perpendicular to the travel path so
as to substantially align substantially all of the sheet-like
product such that the sides of the stack are substantially parallel
to one another and orthogonal to the leading and trailing ends.
4. (canceled)
5. The method of claim 3, wherein the step of squeezing the stack
in a transverse direction is performed by passing the stack between
a pair of transversely offset side guides that extend parallel to
one another and parallel to the travel path; and wherein the stack
is pushed between the side guides by the second paddle.
6. The method of claim 1, further comprising independently
controlling the position of the first and second paddles along the
travel path.
7. (canceled)
8. The method of claim 7, The method of claim 6 further comprising
dispensing the stacks from the stack aligner; and wherein the
stacks are fed to the stack aligner at a first speed along the
travel path and are dispensed from the stack aligner at a second
speed along the travel path, different than the first speed.
9. A method of aligning stacks of a stream of stacks as the stacks
travel through a stack aligner as the stacks travel along a stack
travel path, each stack including a plurality of stacked sheet-like
products, each stack generally having a downstream leading end, an
upstream trailing end, a pair of sides extending between the
leading end and the trailing end, a top and a bottom, the method
comprising: feeding the stream of stacks to the stack aligner with
a gap formed between adjacent stacks, inserting a paddle of the
stack aligner into each gap between adjacent stacks, such that each
stack has a paddle upstream of the stack and a paddle downstream
from the stack; and pressing each stack between the paddle upstream
of the stack and the paddle downstream of the stack so as to
substantially align all of the sheet-like product such that the
leading end and trailing end of the stack are substantially
parallel to one another and orthogonal to the stack travel
path.
10. The method of claim 9, further comprising changing the spacing
between the paddle upstream of the stack and the paddle downstream
of the stack such that the paddle downstream of the stack no longer
contacts the stack and the stack is pushed by the paddle upstream
of the stack.
11-13. (canceled)
14. The method of claim 9, further comprising independently
controlling the position of the first and second paddles along the
stack travel path.
15. (canceled)
16. The method of claim 9, further comprising increasing a number
of accumulated stacks within the stack aligner: wherein increasing
a number of accumulated stacks within the stack aligner includes:
feeding the stream of stacks to the stack aligner with a gap formed
between adjacent stacks at an average feed rate but with an
inconsistent gap width between adjacent stacks; and dispensing the
stacks at an outlet end of the stack aligner at an average
dispensing rate with a substantially equal spacing between adjacent
stacks, the supply rate being greater than the dispensing rate.
17-20. (canceled)
21. The method of claim 9, wherein each paddle remains in a
substantially orthogonal orientation relative to the stack travel
path as the paddle is inserted into a corresponding gap between
adjacent stacks.
22. The method of claim 21 further including retracting each paddle
from the corresponding gap between each adjacent stack and wherein
each paddle remains in a substantially orthogonal orientation
relative to the stack travel path as the paddle is retraced from
the corresponding gap between adjacent stacks.
23. A method of transporting stacks of a stream of stacks from a
log saw where the stacks are formed from a plurality of longer logs
to a wrapper for wrapping the stacks, each stack including a
plurality of stacked sheet-like products, each stack generally
having a downstream leading end, an upstream trailing end, a pair
of sides extending between the leading end and the trailing end, a
top and a bottom, the method comprising feeding the stacks to a
stack aligner as the stacks travel along a stack travel path at a
stack aligner inlet; dispensing the stacks from the stack aligner
at a stack aligner outlet; sensing a position of each stack prior
to feeding the stack to the stack aligner; calculating a motion
profile to insert a paddle of the stack aligner after each
stack.
24. The method of claim 23, further comprising receiving the stacks
at an inlet end of the stack aligner at an average supply rate but
with unequal spacing between adjacent stacks; and dispensing the
stacks at an outlet end of the stack aligner at an average
dispensing rate with a substantially equal spacing between adjacent
stacks.
25-26. (canceled)
27. A stack aligner for aligning stacks of a stream of stacks as
the stacks travel along a stack travel path, adjacent ones of the
stacks being longitudinally spaced apart along the stack travel
path forming a gap therebetween, each stack including a plurality
of stacked sheet-like products, each stack generally having a
downstream leading end, an upstream trailing end, and a pair of
sides extending between the leading end and the trailing end, the
stack aligner comprising: a plurality of paddles configured for
being inserted into the gap between adjacent stacks; a guide
arrangement for guiding the paddles along a paddle travel path, the
paddle travel path having a portion thereof that is coincident with
a portion of the stack travel path; a control arrangement
configured to independently control the motion of the paddles along
the paddle travel path.
28. The stack aligner of claim 27, wherein the control arrangement
is configured to control the motion of the of the plurality of
paddles such that when adjacent paddles have been inserted into
corresponding gaps, the control arrangement reduces the spacing
between adjacent paddles such that the paddles press the stack
positioned therebetween between the paddle upstream of the stack
and the paddle downstream of the stack so as to substantially align
all of the sheet-like product such that the leading end and
trailing end of the stack are substantially parallel to one another
and orthogonal to the stack travel path.
29-30. (canceled)
31. The stack aligner of claim 27, wherein: the guide arrangement
includes: a carriage track that defines a closed guide path; a
first cam track; a second cam track; each paddle is pivotally
attached to a guide carriage that is guided by the carriage track
along the closed guide path, each paddle is operably coupled to
first and second cam followers; the first cam follower and the
first cam track are configured to rotate the paddle relative to the
guide carriage at least 75 degrees; and the second cam follower and
the second cam track are configured to rotate the paddle relative
to the guide carriage at least 75 degrees.
32. The stack aligner of claim 27, wherein: the guide arrangement
includes: a carriage track that defines a closed guide path; a cam
track arrangement; each paddle is pivotally attached to a guide
carriage that is guided by the carriage track along the closed
guide path for motion in a single direction, each paddle is
operably attached to a cam follower arrangement; the cam track
arrangement and cam follower arrangement are configured to rotate
the paddle relative to the carriage track and the closed guide path
while inserting the paddle between adjacent stacks; and the cam
track arrangement and cam follower arrangement are configured to
rotate the paddle relative to the carriage track and the closed
guide path while removing the paddle from between adjacent
stacks.
33. The stack aligner of claim 32, wherein: the cam track
arrangement and cam follower arrangement are configured to rotate
the paddle relative to the corresponding guide carriage in a first
angular direction while inserting the paddle between adjacent
stacks; and the cam track arrangement and cam follower arrangement
are configured to rotate the paddle relative to the corresponding
guide carriage in the first angular direction while removing the
paddle from between adjacent stacks.
34. The stack aligner of claim 33, wherein the cam track
arrangement and cam follower arrangement are configured to rotate
the paddle relative to the corresponding guide carriage in a second
angular direction after the paddle has been removed from between
adjacent stacks to prepare the paddle to be inserted into another
gap between another pair of adjacent stacks.
35. The stack aligner of claim 32, wherein: the cam track
arrangement and cam follower arrangement are configured to rotate
the paddle relative to the carriage track and the closed guide path
such that the paddle remains substantially orthogonal to the stack
travel path as the paddle is inserted into the gap; and the cam
track arrangement and cam follower arrangement are configured to
rotate the paddle relative to the carriage track and the closed
guide path such that the paddle remains substantially orthogonal to
the stack travel path as the paddle is removed from the gap.
36. (canceled)
37. The stack aligner of claim 32, wherein: the first cam follower
and the first cam track are configured to maintain upstream and
downstream contact surfaces of the paddle in a substantially
orthogonal orientation relative to the stack travel path as the
paddles are transitioned into a gap between adjacent stacks; and
the second cam follower and the second cam track are configured to
maintain the upstream and downstream contact surfaces of the paddle
in a substantially orthogonal orientation relative to the stack
travel path as the paddles are transitioned out of the gap between
adjacent stacks.
38. (canceled)
39. The stack aligner of claim 27, wherein the control arrangement
is configured to control the motion of the of the plurality of
paddles such that after adjacent paddles have pressed a stack
positioned therebetween, the longitudinal spacing along the paddle
travel path, as well as the stack travel path, between the adjacent
paddles is increased so that only the trailing end of the stack is
contacted the paddle upstream from the corresponding stack.
40. The stack aligner of claim 27, wherein the control arrangement
is configured to independently control the motion of the paddles
such that the positional tolerance of each stack along the stack
travel path after the stack is no longer controlled by a paddle of
the stack aligner is less than 0.25 inches.
41. The stack aligner of claim 27, wherein the motion of the
paddles is not mechanically tied to one another such that each
paddle can be independently accelerated along the paddle travel
path.
42. The stack aligner of claim 27, further comprising an in feed
conveyor; an out feed conveyor and a low friction surface
interposed between the in feed conveyor and the out feed conveyor.
Description
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS
[0001] This patent application claims the benefit of U.S.
Provisional Patent Application No. 61/879,236, filed Sep. 18, 2013,
the entire teachings and disclosure of which are incorporated
herein by reference thereto.
FIELD OF THE INVENTION
[0002] This invention generally relates to systems for forming
wrapped stacks of sheet-like product, and particularly to an
alignment apparatus for aligning stacks of sheet-like product prior
to being wrapped into packs.
BACKGROUND OF THE INVENTION
[0003] Many sheet-like products such as, for example, napkins,
facial tissues or paper towels are stacked and then wrapped for
shipment. Many wrapping arrangements for wrapping the stacks
process the stacks in a single-file orientation.
[0004] The wrapping process and wrapping arrangements do not
tolerate large variations in the spacing between stacks or
variations in the shape/squareness of the stacks. As such, it is
desirable to feed stacks to the wrapping arrangement at a constant
interval with the stacks in a desired position along the path along
which the stacks are fed to the stacking arrangement. Also, it is
desired for the stacks to have all of the sheets properly aligned
such that the sides of the stacks are generally planar.
[0005] As the speed of production of the stacks of sheet-like
product increases it becomes more and more difficult to maintain
the squareness of the stacks as well as the accuracy of the stacks
along the stack travel path.
[0006] Further, many stacks are formed from cutting the stack (also
referred to as a clip) from a larger log of stacks of sheet-like
product, typically longer. These logs will typically pass through
and be cut by a cutting arrangement which is typically a log saw.
These logs are often produced and supplied to the log saw at
varying intervals which causes further variation in the spacing and
positional accuracy of the stream of stacks supplied to the
wrapping arrangement.
[0007] Embodiments of the present invention relate to improvements
in the current state of the art.
BRIEF SUMMARY OF THE INVENTION
[0008] A new and improved system for forming wrapped stacks of
sheet-like product is provided. Methods of aligning sheets within a
stack of sheet-like product are also provided.
[0009] In one particular embodiment, a method of aligning a stack
of a plurality of vertically stacked sheet-like products as the
stack travels along a travel path as the stack travels through a
stack aligner as the stack travels along the travel path is
provided. The stack has a downstream leading end, an upstream
trailing end, a pair of sides extending between the leading end and
the trailing end, a top and a bottom.
[0010] The method includes feeding the stack to the stack aligner,
pressing the stack between a first paddle of the stack aligner that
is downstream from the stack and a second paddle of the stack
aligner that is upstream from the stack so as to substantially
align all of the sheet-like product such that the leading end and
trailing end of the stack are substantially parallel to one another
and orthogonal to the travel path.
[0011] In one method, the method further includes the step of
pushing the stack out of the stack aligner using the second
paddle.
[0012] In one method, the method further includes squeezing the
stack in a transverse direction that is perpendicular to the travel
path so as to substantially align substantially all of the
sheet-like product such that the sides of the stack are
substantially parallel to one another and orthogonal to the leading
and trailing ends.
[0013] In one embodiment, the step of squeezing the stack in a
transverse direction is performed by passing the stack between a
pair of transversely offset side guides that extend substantially
parallel to one another and parallel to the travel path. Typically,
the stack is pushed between the side guides by the second
paddle.
[0014] In one embodiment, the method includes independently
controlling the position of the first and second paddles along the
travel path. After aligned, a method includes dispensing the stacks
from the stack aligner.
[0015] In one embodiment, the stacks are fed to the stack aligner
at a first speed along the travel path and are dispensed from the
stack aligner at a second speed along the travel path. The second
speed may be slower or faster than the first speed depending on the
operating parameters of the system.
[0016] In one embodiment, a further method of aligning stacks of a
stream of stacks as the stacks travel through a stack aligner as
the stacks travel along a travel path is provided. Each stack has a
plurality of stacked sheet-like products. Each stack generally has
a downstream leading end, an upstream trailing end, a pair of sides
extending between the leading end and the trailing end, a top and a
bottom.
[0017] The method includes feeding the stream of stacks to the
stack aligner with a gap formed between adjacent stacks; inserting
a paddle of the stack aligner into each gap between adjacent
stacks, such that each stack has a paddle upstream of the stack and
a paddle downstream from the stack as the stacks travel through the
stack aligner. The method also includes pressing each stack between
the paddle upstream of the stack and the paddle downstream of the
stack so as to substantially align all of the sheet-like product
such that the leading end and trailing end of the stack are
substantially parallel to one another and orthogonal to the travel
path.
[0018] In one embodiment, the method also includes changing the
spacing between the paddle upstream of the stack and the paddle
downstream of the stack such that the paddle downstream of the
stack no longer contacts the stack and the stack is pushed by the
paddle upstream of the stack. This operation occurs after the step
of squeezing. This can be done by increasing the speed of the
downstream paddle or reducing the speed of the upstream paddle.
This decision can be decided on the overall number of stacks
accumulated within the stack aligner.
[0019] In one embodiment, the method further includes squeezing
each stack in a transverse direction that is perpendicular to the
travel path so as to substantially align all of the sheet-like
product of a given stack such that the sides of a given stack are
substantially parallel to one another and orthogonal to the leading
and trailing ends of the stack.
[0020] In one embodiment, the step of squeezing each stack in a
transverse direction is performed by passing the stacks between a
pair of transversely offset side guides that extend generally
parallel to one another and parallel to the travel path.
[0021] In one embodiment, the stack is pushed between the side
guides by the second paddle.
[0022] In one embodiment, the method includes independently
controlling the position of the first and second paddles along the
travel path.
[0023] In one embodiment, the method is configured for accumulating
stacks and the method includes increasing a number of accumulated
stacks within the stack aligner.
[0024] In one embodiment, increasing a number of accumulated stacks
within the stack aligner includes: feeding the stream of stacks to
the stack aligner with a gap formed between adjacent stacks at an
average feed rate but with an inconsistent gap width between
adjacent stacks; and dispensing the stacks at an outlet end of the
stack aligner at an average dispensing rate with a substantially
equal spacing between adjacent stacks, the supply rate being
greater than the dispensing rate.
[0025] In one embodiment, the step of feeding the stream of stacks
to the stack aligner with a gap formed between adjacent stacks
includes feeding the stream of stacks to the stack aligner at an
average feed rate with inconsistent gap widths between sets of
adjacent stacks; and further includes dispensing the stacks at an
outlet end of the stack aligner at an average dispensing rate with
substantially consistent gap widths between adjacent stacks.
[0026] In one embodiment, the average feed rate is substantially
equal to the average dispensing rate.
[0027] In one embodiment, the average feed rate is less than the
average dispensing rate such that a number of stacks within the
stack aligner decreases. In one embodiment, the average feed rate
is greater than the average dispensing rate such that a number of
stacks within the stack aligner increases. Additionally, the system
may switch between accumulating stacks and reducing the number
within the stack aligner.
[0028] In one embodiment, each paddle travels in a substantially
orthogonal direction relative to the travel path as the paddle is
inserted into a corresponding gap between adjacent stacks. In one
embodiment, the method includes retracting each paddle from the
corresponding gap between each adjacent stack and wherein each
paddle travels in a substantially orthogonal direction relative to
the travel path as the paddle is retraced from the corresponding
gap between adjacent stacks.
[0029] In another embodiment, a method of transporting stacks of a
stream of stacks from a log saw where the stacks are formed from a
plurality of longer logs to a wrapper for wrapping the stacks is
provided. Each stack including a plurality of stacked sheet-like
products, each stack generally having a downstream leading end, an
upstream trailing end, a pair of sides extending between the
leading end and the trailing end, a top and a bottom.
[0030] The method includes feeding the stacks to a stack aligner as
the stacks travel along a stack travel path at a stack aligner
inlet; dispensing the stacks from the stack aligner at a stack
aligner outlet; sensing a position of each stack prior to feeding
the stack to the stack aligner; calculating a motion profile to
insert a paddle of the stack aligner after each stack.
[0031] In one embodiment, the method further includes receiving the
stacks at an inlet end of the stack aligner at an average supply
rate but with unequal spacing between adjacent stacks; and
dispensing the stacks at an outlet end of the stack aligner at an
average dispensing rate with a substantially equal spacing between
adjacent stacks.
[0032] In one embodiment, the average supply rate is substantially
equal to the average dispensing rate.
[0033] In one embodiment, the method includes independently
controlling the motion of each of the paddles.
[0034] A stack aligner for aligning stacks of a stream of stacks as
the stacks travel along a stack travel path is provided. Adjacent
ones of the stacks are longitudinally spaced apart along the travel
path forming a gap therebetween. Each stack includes a plurality of
stacked sheet-like products. Each stack generally has a downstream
leading end, an upstream trailing end, and a pair of sides
extending between the leading end and the trailing end.
[0035] The stack aligner includes a plurality of paddles, a guide
arrangement and a control arrangement. The paddles are configured
for being inserted into the gap between adjacent stacks. The guide
arrangement guides the paddles along a paddle travel path. The
paddle travel path having a portion thereof that is coincident with
a portion of the stack travel path. The control arrangement is
configured to independently control the motion of the paddles along
the paddle travel path. As such, the paddles can control the speed
of the stacks through the coincident portion of the travel paths at
different speeds. This allows for improved positional accuracy of
the stacks as well as improving the squareness of the stacks.
[0036] In one embodiment, the control arrangement is configured to
control the motion of the of the plurality of paddles such that
when adjacent paddles have been inserted into corresponding gaps
the control arrangement reduces the spacing between adjacent
paddles such that the paddles press the stack positioned
therebetween between the paddle upstream of the stack and the
paddle downstream of the stack so as to substantially align all of
the sheet-like product such that the leading end and trailing end
of the stack are substantially parallel to one another and
orthogonal to the travel path.
[0037] In one embodiment, the stack aligner includes a pair of side
guides transversely offset from one another and that generally
extend longitudinally along the stack travel path. The side guides
may be transversely spaced apart a distance equal to a width of the
stacks from side to side, slightly greater than the width of the
stacks or slightly less than the width of the stacks.
[0038] In one embodiment, the side guides remain in a substantially
fixed position while the stacks pass therebetween.
[0039] In one embodiment, the guide arrangement includes a carriage
track that defines a closed guide path; a first cam track and a
second cam track. Each paddle is pivotally attached to a guide
carriage that is guided by the carriage track along the closed
guide path. Each paddle is operably coupled to first and second cam
followers. The first cam follower and the first cam track are
configured to rotate the paddle relative to the carriage track and
the closed guide path at least 60 degrees, preferably at least 75
degrees, more preferably at least 80 degrees and even more
preferably at least 85 degrees and desirably about 90 degrees. The
second cam follower and the second cam track are configured to
rotate the paddle relative to the carriage track and the closed
guide path at least 60 degrees, preferably at least 75 degrees,
more preferably at least 80 degrees and even more preferably at
least 85 degrees and desirably about 90 degrees.
[0040] In one embodiment, the guide arrangement includes a carriage
track that defines a closed guide path and a cam track arrangement.
Each paddle is pivotally attached to a guide carriage that is
guided by the carriage track along the closed guide path for motion
in a single direction. Each paddle is operably attached to a cam
follower arrangement. The cam track arrangement and cam follower
arrangement are configured to rotate the paddle relative to the
carriage track and the closed guide path while inserting the paddle
between adjacent stacks. The cam track arrangement and cam follower
arrangement are configured to rotate the paddle relative to the
carriage track and the closed guide path while removing the paddle
from between adjacent stacks.
[0041] In a more particular embodiment, the cam track arrangement
and cam follower arrangement are configured to rotate the paddle
relative to the carriage track and the closed guide path
approximately 90 degrees in a first angular direction while
inserting the paddle between adjacent stacks; and the cam track
arrangement and cam follower arrangement are configured to rotate
the paddle relative to the carriage track and the closed guide path
in the approximately 90 degrees while removing the paddle from
between adjacent stacks.
[0042] In one embodiment, the cam track arrangement and cam
follower arrangement are configured to rotate the paddle relative
to the carriage track and the closed guide path such that the
paddle remains substantially orthogonal to the stack travel path as
the paddle is inserted into the gap; and the cam track arrangement
and cam follower arrangement are configured to rotate the paddle
relative to the carriage track and the closed guide path such that
the paddle remains substantially orthogonal to the stack travel
path as the paddle is removed from the gap.
[0043] In one embodiment, the first and second cam tracks are
transversely offset from one another in a direction perpendicular
to the stack travel path.
[0044] In one embodiment, the first cam follower and the first cam
track are configured to maintain upstream and downstream contact
surfaces of the paddle in a substantially orthogonal orientation
relative to the stack travel path as the paddles are transitioned
into and enters a gap between adjacent stacks; and the second cam
follower and the second cam track are configured to maintain the
upstream and downstream contact surfaces of the paddle in a
substantially orthogonal orientation relative to the stack travel
path as the paddles are transitioned out of and exits a gap between
adjacent stacks.
[0045] In one embodiment, the first and second cam followers and
first and second cam tracks are configured to maintain the upstream
and downstream contact surfaces orthogonal to the stack travel path
substantially the entire time that the paddle travel path is
coincident with the stack travel path.
[0046] In one embodiment, the control arrangement is configured to
control the motion of the of the plurality of paddles such that
after adjacent paddles have pressed a stack positioned
therebetween, the longitudinal spacing along the paddle travel
path, as well as the stack travel path, between the adjacent
paddles is increased so that only the trailing end of the stack is
contacted the paddle upstream from the corresponding stack.
[0047] In one embodiment, the control arrangement is configured to
independently control the motion of the paddles such that the
positional tolerance of each stack along the stack travel path
after the stack is no longer controlled by a paddle of the stack
aligner is less than +/-0.25 inches.
[0048] In one embodiment, the motion of the paddles is not
mechanically tied to one another such that each paddle can be
independently accelerated along the paddle travel path.
[0049] In one embodiment, the stack aligner includes an in feed
conveyor, an out feed conveyor and a low friction surface. The low
friction surface is interposed between the in feed conveyor and the
out feed conveyor.
[0050] Other aspects, objectives and advantages of the invention
will become more apparent from the following detailed description
when taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0051] The accompanying drawings incorporated in and forming a part
of the specification illustrate several aspects of the present
invention and, together with the description, serve to explain the
principles of the invention. In the drawings:
[0052] FIG. 1 is a simplified schematic illustration of a pack
forming system;
[0053] FIG. 2 is a simplified illustration of a stack of sheet-like
product that is formed and wrapped in the pack forming system of
FIG. 1;
[0054] FIG. 3 is a partial illustration of an embodiment of a stack
aligner of the system of FIG. 1;
[0055] FIG. 4 is a simplified schematic illustration of the stack
aligner of FIG. 3 in operation;
[0056] FIGS. 5 and 6 illustrate a slightly modified embodiment of
the stack aligner of FIGS. 3 and 4 illustrating the stack aligner
in a maximum accumulation state (FIG. 5) and a minimum accumulation
state (FIG. 6);
[0057] FIG. 7 is a simplified control algorithm for controlling the
stack aligner; and
[0058] FIGS. 8-11 are more detailed control schematics for the
control algorithm of FIG. 7.
[0059] While the invention will be described in connection with
certain preferred embodiments, there is no intent to limit it to
those embodiments. On the contrary, the intent is to cover all
alternatives, modifications and equivalents as included within the
spirit and scope of the invention as defined by the appended
claims.
DETAILED DESCRIPTION OF THE INVENTION
[0060] FIG. 1 is a schematic illustration of a pack forming system
100 according to an embodiment of the present invention. The pack
forming system 100 is configured to form and then wrap stacks of
sheet-like product such as napkins or facial tissue to form packs
of sheet-like product. Typically, the pack forming system 100 will
receive a web of material and convert the web of material into the
packs of sheet-like product.
[0061] The illustrated pack forming system 100 includes a folding
arrangement 102 that receives a continuous web of material and cuts
the web into individual sheets and stacks the sheets to form logs
104. The sheets within the logs 104 may be folded any number of
times. Further, adjacent sheets in the logs may be interfolded or
merely in a stacked configuration and not interfolded. Preferably,
adjacent sheets are vertically stacked. However, embodiments of the
invention are not so limited and in some embodiments, the sheets
may be vertically oriented such that the sheets rest on edges
thereof and are stacked horizontally.
[0062] In some embodiments, the length of the logs may be in excess
of 8 feet.
[0063] The logs 104 are transported downstream to a cutting
mechanism. The cutting mechanism is in the form of a log saw 106.
The log saw 106 cuts the logs 104 into individual stacks 108 (a
stack 108 may also be referred to as a "clip"). A typical log 106
may be cut into 5 to 15 separate stacks 108. However larger logs or
smaller stacks may result in more stacks per log.
[0064] Adjacent stacks 108 downstream from the log saw 106 are
typically spaced apart along a stack travel path 112 forming gaps
110 therebetween.
[0065] The stream of stacks 108 travel along the stack travel path
112 downstream from the cutting mechanism to a pack aligner 114.
The stack aligner 114 is configured to square up or otherwise
straighten the sheets within the pack as well as to provide
consistent spacing between the stacks 108 and proper positional
location of the stacks 108 along the stack travel path in
preparation for wrapping.
[0066] After passing the pack aligner 14, the stacks 118 travel
along the stack travel path 112 to a wrapping arrangement 116. In a
preferred embodiment the wrapping arrangement 116 is a progressive
wrapper. Typically, the stacks 108 are wrapped in a clear plastic
material. However, other wrapping arrangements could be
incorporated that are not progressive wrappers or that utilize
other materials such as other plastic or paper materials. The
wrapped stacks form individual packs 118. The packs 118 will travel
downstream where they can be further packaged for shipment.
[0067] Other folding arrangements 102 are contemplated. For
instance, rather than forming logs of sheets that need to be cut
into individual clips or stacks, the folding arrangement could
directly form individual stacks of sheet-like product such that a
cutting mechanism is not required between the folding arrangement
and the stack aligner. In such an embodiment, a plurality of lanes
of stacks may be formed. Because the stacks 108 must pass through
the wrapping arrangement 116 in single file, a stack merger (not
shown) may be interposed between the folding arrangement and the
stack aligner 114 if only a single wrapping arrangement 116 is
provided in the system.
[0068] It is desired to supply the stream of stacks 108 to the
wrapping arrangement 116 with a position tolerance less than
+/-0.05 inches. The position tolerance for various mechanisms
upstream from the pack aligner can range from +/-0.25 inches to in
excess of +/-1 inch depending on the type of sheet-like product or
the upstream processes used to produce the single file stream of
stacks 108. This positional tolerance can provide significant
problems with the wrapping process. The stack aligner 114 can
rectify this low tolerance to improve the operation of the wrapping
arrangement 116 and provide tolerance of less than +/-0.25.
[0069] For reference, FIG. 2 illustrates a simplified
representative stack 108. The stack has a plurality of sheets 124.
The sheets 124 may have one or more panels. If a plurality of
panels are provided the panels would be connected to one another by
a fold, as is generally well known. The sheets 124 are stacked
generally vertically on top of one another. Vertically on top of
one another shall include having adjacent ones of the sheets 104
interfolded with one another.
[0070] The stack 108 generally includes a downstream leading end
126 that is generally parallel to an upstream trailing end 128. A
pair of opposed sides 130, 132 extend generally parallel to one
another and between leading and trailing ends 126, 128. A top side
134 extends generally parallel to a bottom side 136. The top and
bottom sides 134, 136 extend generally perpendicular to the opposed
sides 130, 132 as well as generally perpendicular to the leading
and trailing ends 126, 128. All of the ends/sides 126, 128, 130,
132, 134, 136 are desirably rectangular and planar.
[0071] With additional reference to FIG. 1, when the stacks 108
travel along the stack travel path 112 upstream of the stack
aligner 114, the leading and trailing ends 126, 128 are generally
orthogonal to the stack travel path 112 and the opposed sides 130,
132 and top and bottom sides 134, 136 are generally parallel to the
stack travel path 112.
[0072] Due to the process upstream from the stack aligner 114 that
form and align the stacks in a single file line for wrapping, the
stacks 108 can be less square than desirable. For instance,
individual sheets 124 could be rotated relative to the stack such
as about a vertical axis 140 that is perpendicular to the panels of
the sheets 124. This will give the stack a twisted configuration.
Additionally, sheets 124 could be shifted forward or backward along
the sheet travel path 112 such as illustrated by arrow 142 such
that some the leading and trailing ends 126, 128 of the stack are
not orthogonal relative to the stack travel path. Additionally, the
sheets 124 can be laterally shifted in a direction perpendicular to
the sheet travel path such as illustrated by arrow 144 such that
the opposed sides 130, 132 are not perpendicular to the top and
bottom sides 134, 136. The stack aligner 114 can also rectify these
deficiencies and square-up the sheets 124 within a stack 108.
[0073] FIG. 3 is a partial illustration of the stack aligner 114.
The stack aligner 114 is used to both square-up the sheets in a
given pack as well as improve the positional tolerances of the
stream of stacks prior to the stacks 108 reaching the wrapping
arrangement 116.
[0074] The stack aligner 114 includes a plurality of paddles 150
that push the stacks 108 through the stack aligner 114. Each paddle
150 is pivotally attached to a guide carriage 152 which is carried
and guided by a carriage track 154. The carriage track 154 defines
a closed guide path along which the guide carriages 152 are guided.
The carriage track 154 and guide carriages 152 are preferably
configured such that the guide carriages 152 are independently
controllable along the guide path defined by the carriage track 154
such that each guide carriage 152 can be accelerated independently
of the rest of the guide carriages 12 mounted to the carriage track
154. In one embodiment, the carriage track 154 and guide carriages
152 form a linear synchronous motor such as provided by Jacobs
Automation Inc of Erlanger, Kentucky.
[0075] The guide track 154 and a pair of cam tracks 156, 158 form a
guide arrangement that guides the motion of the paddles 150 through
a paddle travel path as the guide carriages 152 travel along the
guide path of the carriage track 154.
[0076] The pair of cam tracks 156, 158 are laterally spaced apart
in a direction perpendicular to the stack travel path 112 such that
the cam tracks are on opposite sides of the carriage track 154 as
well as opposite sides of the paddles 150 and guide carriages 152.
The paddles 150 are fixedly attached to corresponding cam followers
157, 159 that cooperate with cam track 156 and cam track 158,
respectively, for rotating the paddles 150 about rotational axis
161.
[0077] The guide arrangement is configured such that the paddles
150 are inserted into the gaps 110 (see FIG. 1) between adjacent
stacks 108 in a substantially orthogonal direction relative to the
stack travel path 112. Front (i.e. downstream) and rear (i.e.
upstream) surfaces 160, 162 of the paddles 150, which are
substantially planar surfaces, remain substantially orthogonal to
the stack travel path 112 as the paddles 150 are inserted into gaps
110. Preferably, the paddles 150 remain substantially vertically
upright while moving in the vertical downward direction illustrated
by arrow 164 as the paddles 150 are inserted in to gap 110 between
adjacent stacks 108.
[0078] This motion of the paddles 150 is controlled by cam track
156 and corresponding cam follower 157. This causes the paddle to
rotate relative to the carriage track 154 and the guide carriage
152 approximately 90 degrees about rotational axis 161 in a first
direction during the insertion process while a paddle 150 is being
inserted into gap 110. This motion transitions the paddle 150 from
the orientation illustrated by paddle 150' to the orientation
illustrated by paddle 150''. However, prior to this motion, cam
track 156 causes the paddles 150 to rotate in a second, opposite,
direction about rotational axis 161 of approximately 90 degrees.
This initial motion transitions the paddle 150 from the orientation
illustrated by paddle 150''' to the orientation illustrated by
paddle 150'.
[0079] Additionally, the guide arrangement is configured such that
the paddles 150 are retracted from the gaps 110 (see FIG. 1)
between adjacent stacks 108 in a substantially orthogonal direction
relative to the stack travel path 112. Front and rear surfaces 160,
162 of the paddles 150 remain substantially orthogonal to the stack
travel path 112 as the paddles 150 are retracted from gaps 110.
Preferably, the paddles 150 remain substantially vertically upright
while moving in the vertical upward direction illustrated by arrow
166 as the paddles 150 are retracted from gap 110 between adjacent
stacks 108.
[0080] This motion of the paddles 150 is controlled by cam track
158 and corresponding cam follower 159. This causes the paddle to
rotate relative to the carriage track 154 and the guide carriage
152 approximately 90 degrees about rotational axis 161 in a the
first direction during the retraction process while the paddle is
being retracted from gap 110. After this initial motion in the
first direction, cam track 158 causes the paddles 150 to rotate in
the second direction about rotational axis 161 of approximately 90
degrees.
[0081] As such, the first cam track 156 is configured to cause the
paddles 150 to undergo rotation in both the first and second
directions about rotational axis 161 while the paddles 150 are
under control of the first cam track 156. Similarly, the second cam
track 158 is configured to cause the paddles 150 to undergo
rotation in both the first and second directions about rotational
axis 161 while the paddles 150 are under control of the second cam
track 156. The first cam track 156 first causes rotation of paddles
150 about axis 161 in the second direction and then in the first
direction. The second cam track 156 first causes rotation of
paddles 150 about axis 161 in the first direction and then in the
second direction.
[0082] The cam tracks 156, 158 have overlapping regions 167 where
the paddles 150 transition from being controlled by one of the cam
tracks 156, 158 to being controlled by the other one of the cam
tracks 158, 156. In the illustrated embodiment, the overlapping
regions 167 exist adjacent a linear section, e.g. straight section,
of the guide track 154 travel path where the paddle 150 extends
orthogonally relative to the guide track 154.
[0083] As the paddle 150 travels around the guide track 154, the
cam tracks 156, 158 will cause the paddle 150 to rotate relative to
guide carriage 152 typically approximately +/-90 degrees from the
perpendicular orientation depending on the particular location
around the guide track 154.
[0084] Typically, the stacks 108 will be fed to the stack aligner
by an in feed conveyor 170 and transferred to a low friction table
172 or other non-moving sliding surface/table upon which the stacks
108 can easily slide. The stacks 108 are pushed along the stack
travel path 112 through the stack aligner 114 by the paddles 150
while the stacks 108 rest and slide on the low friction table 172.
The paddles 150 will push the stacks 108 out of the stack aligner
114 onto an out feed conveyor 174 which transport the stacks
downstream to the wrapping arrangement 116. The in feed and out
feed conveyors 170, 174 are preferably compression conveyors that
each have a top and bottom conveyor that vertically compresses the
stacks 108 therebetween as the stacks travel along the stack travel
path 112 into and out of the stack aligner 114.
[0085] The stack aligner 114 further includes a pair of side guides
176 that laterally squeeze the stacks 108 as the stacks 108 pass
along the stack travel path 112 through the stack aligner 114. The
side guides 176 help align the stacks 108 by constraining the
sheets of the stacks in a direction that is generally perpendicular
to the sheet travel path. The side guides 176 typically, at least
initially, taper towards one another in a downstream direction.
[0086] To push the stacks 108 through the stack aligner, a portion
of the paddle travel path, i.e. the path the paddles 150 travel as
the guide carriages 152 travel around the carriage track 154, is
coincident with the stack travel path 112.
[0087] The stack aligner 114 includes a controller 178 that
controls the motion profile of the individual paddles 150 by
controlling the motion profile of the guide carriages 152 along the
carriage track 154. More particularly, the controller 178 will
typically control the speed and acceleration of the guide carriages
152 along the guide path defined by the carriage track 154. The
controller 178, guide track 154 and guide carriages 152 are
configured such that the motion profile of each of the guide
carriages 152, i.e. speed and acceleration thereof, can be
independently controlled.
[0088] In operation, after paddles 150 are inserted both downstream
of and upstream of a particular stack 108, the controller 178 will
control the paddles 150 such that the paddles 150 will reduce the
distance therebetween and press on the leading and trailing ends
126, 128 of the stacks 108 to further facilitate squaring-up the
stacks 108.
[0089] The stacks 108 are discharged from the stack aligner 114 and
dispensed onto the out feed conveyor 174. Once the stacks 108 are
fully under the control of the out feed convey 174, the controller
178 will slow the motion of the paddles 150 along the stack travel
path such that the paddle 150 no longer contacts or pushes the
corresponding stack 108 and then the paddle 150 moves in the
orthogonal direction out of the gap 110 between adjacent stacks in
which the paddle 150 is positioned.
[0090] The operation of the stack aligner 114 will be described in
more detail with additional reference to FIG. 4. The stacks 108 are
moving from left to right and are moving along the stack travel
path 112 as illustrated by arrow 180.
[0091] Paddle 150A is accelerating vertically downward between
stacks 108A and 108B into gap 110A and beginning to accelerate
forward in a downstream direction relative to the stack travel path
112. The paddle 150A is substantially vertically oriented and
substantially orthogonal to the stack travel path 112 so as to
avoid contacting either of stacks 108A, 108B during the insertion
process. Paddle 150A is beginning to rotate angularly about axis
161A relative to guide carriage 152A in an angular clockwise
direction as illustrated by arrow 200A so as to maintain the
vertical/orthogonal orientation relative to the stack travel path
112 during the insertion process.
[0092] Paddle 150B has rotated relative to guide carriage 152B
about axis 161B and is partially between stacks 108B and 108C and
positioned within gap 110B. It is ideally equally spaced from the
leading end of stack 108B and trailing end of stack 106C during the
insertion process. Paddle 150B has a downstream component of motion
that moves the paddle 150B downstream relative to stack travel path
112 as well as a vertical/orthogonal component of motion that moves
the paddle 150B further into gap 110B while rotating about axis
161B to maintain the vertical/orthogonal orientation of the paddle
150B to avoid premature contact with either of stacks 108B,
108C.
[0093] Paddle 150B will travel at a faster speed along the stack
travel path 112 until the downstream surface of paddle 150B
contacts the upstream end of stack 108C, such as paddle 150D
relative to stack 108E.
[0094] The position of stack 108D is controlled by in feed conveyor
170 until the stack 108D crosses junction 202 between in feed
conveyor 170 and sliding table 172, at which time the motion of
stack 108D will be provided by paddle 150C as paddle 150C presses
against the upstream end of stack 108D. Paddle 150D and stack 108E
illustrate such an arrangement where the stack 108E is being pushed
along the stack travel path 112 by the paddle 150D, rather than in
feed conveyor 170.
[0095] At this time, stack 108E is illustrated as being axially
squeezed and captivated between the downstream front surface of
paddle 150D and an upstream rear surface of paddle 150E. This
vertically squares the leading and trailing ends of stack 108E.
Stack 108E will also pass through side guides 176 (not shown in
FIG. 4) to square up the opposed sides 130, 132 of the stack 108E
in a direction perpendicular to stack travel path 112 and
perpendicular to the vertical direction, i.e. in a direction
generally parallel to top and bottom sides 134, 136. To square up
the stack 108E between paddles 150D, 150E, the distance between the
adjacent surfaces of paddles 150D, 150E is reduced to a length
along the stack travel path 112 that is slightly less than the
relaxed length of stack 108E.
[0096] After stack 108E is squared up by being squeezed between
paddles 150D, 150E, paddle 150E accelerates stack 108108F to match
the linear speed of out feed conveyor 174. Not only does paddle
150E many the linear speed of stack 108F with the linear speed of
out feed conveyor 174, paddle 150E properly linearly positions the
stack 108F along the stack travel path 112. This acceleration
separates paddle 150E from the downstream leading end of stack 108E
such that stack 108E is fully controlled only by paddle 150D as
stack 108E travels along the stack travel path 112.
[0097] Paddle 150F has completed this acceleration and is pushing
stack 108G out feed conveyor 174 as the stack 108G is illustrated
as crossing junction 204 between sliding table 172 and out feed
conveyor 174. Stack 108G enters out feed conveyor 174 at the same
speed as the out feed conveyor 174 and at the desired linear
position along stack travel path 112.
[0098] Paddle 150G has fully pushed stack 108H on to out feed
conveyor 174 and its speed component parallel to stack travel path
112 has reduced compared to out feed conveyor 174 such that a gap
is formed between the trailing end of stack 108H and the downstream
front surface of paddle 150G. Paddle 150G is transitioning
vertically/orthogonally out from between stacks 108G and 108H in a
substantially orthogonal direction to, again, prevent undesirable
contact between the paddle 150G and adjacent stacks 108G, 108H as
the paddle 150G is being retracted. As the paddle 150G is being
retracted, the paddle 150G rotates angularly about axis 161G in the
clockwise direction as represented by arrow 200G.
[0099] The paddles 150 will rotate approximately 180 degrees around
the corresponding rotational axis 161 in the clockwise direction
(illustrated by arrows 200A, 200G) from the begging of the entry
process (see e.g. paddle 150A) to the end of the exiting process
(e.g. slightly past the location of Paddle 150G) where the paddle
150 has been removed from the gap 110 between adjacent stacks
108.
[0100] Paddle 1501 has begun to rotate angularly about axis 1611 in
an opposite angular direction, i.e. counter-clockwise as
illustrated by arrow 206. The paddles 150 will rotate approximately
180 degrees around the corresponding rotational axis 161 in the
counterclockwise direction 206 after the paddle 150 has been
removed from the gap 110 between adjacent stacks 108.
[0101] The motion profile of each of the guide carriages 152, and
thus each of the attached paddles 150, is independently controlled
by controller 178. Further, the position of each guide carriage 152
(and attached paddle 150) is continuously monitored. Because each
guide carriage 152 is independently controlled and positionally
monitored, the positional tolerances of the stacks 108 along the
stack travel path 112 as the stacks 108 are dispensed on to out
feed conveyor 174 is very tight. It is desired that the position of
the stacks 108 is approximately +1-0.1 inch after the stacks 108
exit the stack aligner. More preferably the positional tolerance of
the stacks 108 along the stack travel path 112 is approximately
+/-0.05 inches.
[0102] This tight positional tolerance of the stacks 108 along the
stack travel path 112 as the stacks 108 exit the stack aligner 114
and, consequently, enter the wrapping arrangement 116 significantly
improves the operation and consistency of the wrapping process by
wrapping arrangement 116.
[0103] When the pack forming system 100 uses a folding arrangement
102 that forms longer logs 104, such as illustrated in FIG. 1, the
spacing between adjacent logs 104 upstream of the log saw 106 will
typically include inconsistent gap lengths. For instance,
individual logs 104 may have a spacing of between about 1 to 5
stack lengths and the gap spacing can vary from one gap to the
next. These gaps may also be expressed in the number of "air cuts"
that the log saw 106 will perform between adjacent logs 104 as no
cuts will occur as the log saw 104 passes between the adjacent logs
104.
[0104] However, the stack wrapping arrangement 116 cannot
accommodate such random spacing. Without an intervening structure
between the log saw 106 and wrapping arrangement 116, the stacks
108 would arrive at the wrapping arrangement 116 in groups with
varying spacing between adjacent groupings of stacks 108.
[0105] The stack aligner 114 can be used to accumulate and control
the stacks 108 in such a configuration such that the stacks arrive
at the wrapping arrangement with equal spacing. As such, the stack
aligner 114 may also be referred to as an accumulator or an
aligner/accumulator.
[0106] In such a system where groups of stacks 108 are formed with
larger spaces formed between groups of stacks 108, i.e. the spacing
due to the spacing between adjacent logs 104 upstream of the log
saw 106, it can be desirous to lengthen the linear section 210
(also referred to as "accumulation section 210") of the stack
aligner 114 (see FIG. 5). By lengthening the linear section 210,
more stacks 108 may be accumulated within the stack aligner 114 to
compensate for the larger gaps and inconsistencies of the upstream
flow of stacks 108 that is being feed from the log saw 106 to the
stack aligner 114.
[0107] FIG. 5 illustrates a stack aligner similar to that of FIG.
4. However, the stack aligner 114 has been stretched parallel to
the stack travel path 112 so as to allow more stacks 108 to be
positioned within the stack aligner 114. FIG. 5 illustrates the
stack aligner 114 at maximum capacity. FIG. 6 illustrates the stack
aligner 114 at significantly less than maximum capacity.
[0108] The stacks 108 enter and leave the stack aligner 114 in the
same manner as discussed above and are squared up as discussed
above. However, the amount of stacks 108 accumulated within the
stack aligner 114 can fluctuate between that shown in FIG. 5
(maximum accumulation) and that shown in FIG. 6 depending on the
consistency of the upstream supply of stacks 108.
[0109] Typically, it is desired to have a minimum of at least two
to four packs of accumulation within the stack aligner 114 at all
times, i.e. as a minimum accumulation, so as to avoid starving the
wrapping arrangement 116.
[0110] FIG. 7 is a flow chart illustrating the control algorithm
300 for the portion of the system 100 that includes the log saw
106, stack aligner 114, and wrapping arrangement 116. In some
embodiments, the portion of the algorithm that utilizes inputs
regarding the log saw 106 could be modified to incorporate
information from an upstream stream of stacks supplied from a stack
merger if a log saw 106 is not incorporated into a system (e.g.
such as in a system for forming napkins).
[0111] The algorithm 300, at block 302, reads the orbit head
position and speed of the log saw 106, the position of a log 104
entering the saw, and calculates the positions of the stacks 108
leaving the log saw 106. The number of stacks per log is entered as
a product code. A sensor 220 (see FIG. 1) checks the position of
each stack along the stack travel path 112 shortly before entering
the stack aligner 114. These inputs along with the number of stacks
108 in the accumulation section 210 are used to control the speed
of the wrapper.
[0112] As noted above, a paddle 150 is inserted behind each stack
108 entering the stack aligner 150. The paddle 150 is inserted a
distance upstream from each stack 108. After being inserted into
the gap 110, the paddle 150 is moved into contact with the trailing
upstream end of the stack. At this point, the preceding paddle 150
slows down to contact the leading downstream end of the stack 108
to square up the stack 108. Alternatively, the trailing paddle 150
speeds up to push the leading end of the stack 108 against the back
side of the preceding paddle to square up the stack 108. These two
paddle motions are used selectively depending on the stat of
accumulation of stacks within the accumulation section 210 of the
stack aligner.
[0113] The algorithm 300 includes a queue manager 304 that performs
three functions. First, the queue manager 304 controls the wrapping
arrangement 116 speed. Second, the queue manager 304 keeps track of
the state of the accumulation of stacks 108 within the stack
aligner 114. Third, the queue manager 304 controls the motion of
the stacks 108 within the stack aligner 114.
[0114] The incoming stream of stacks is categorized as full, small
gap, or large gap. A full incoming stack stream consists of stacks
from one log. A small gap stack stream consists of a gap between
consecutive logs where the logs 104 are supplied to the log saw
with the minimum gaps between logs. A small gap is typically 2 to 4
log saw orbits (e.g. air cuts) between consecutive logs 104. A
large gap is a gap in the supply of logs 104.
[0115] The accumulator state is the number of stacks 108 within the
accumulation section 210, the position of each stack 108, and the
velocity of each stack 108. The position and velocity of each stack
within the stack aligner 114 along the stack travel path 112 is
inferred from the position and velocity of the paddles 150. The
electronics that control the motion of the guide carriages 152
measure the velocity and position of the guide carriages 152 and
consequently the paddles 150. When the accumulation section 210 is
full, stacks 108 flow from entry to exit with minimum or no gap
between stacks 108 within the stack aligner 114 (see e.g. FIG. 5).
When the accumulation section 210 is empty, each stack 108 enters
the stack aligner 114, is aligned, and then immediately and quickly
moved to the exit and onto the out feed conveyor 174. When the
accumulation section 210 is partially filled to some extent between
maximum and minimum accumulation, operation is controlled to an
intermediate degree or degrees. For instance, the operation could
be controlled as a ratio based on the accumulation state of the
accumulation section 210.
[0116] The queue manager controls the speed of the wrapping
arrangement 116 according to the queue state and incoming stack
stream. The table of FIG. 10 summarizes the algorithm for
controlling the speed of the wrapping arrangement 116. The gap
between adjacent logs 104, as mentioned above, is normally not
constant, therefore the speed of the wrapping arrangement 116 must
vary to follow the flow of stacks 108.
[0117] The stack discharge algorithm, with reference to FIG. 11,
reads the speed and phase of the wrapper, along with the position
of the next stack to be discharged from the accumulation section
210, and calculates a motion profile to put that stack 108 onto the
out feed conveyor 174 at correct speed and position along the stack
travel path 112. When the stack is fully on the out feed conveyor
174, the corresponding paddle 150 slows to clear the trailing end
of the stack 108 and moves up and away as discussed above.
[0118] The ability to independently control the guide carriages 152
and consequently paddles 150 allows for the ability to adjust the
flow of the stacks out of the stack aligner 114 independent of the
flow of stacks 108 into the stack aligner 114, within the limits of
the amount of stacks 108 that can be accumulated within the stack
aligner 114. This is a significant upgrade over the prior art that
typically utilized a fixed paddle conveyor where if the speed of
the wrapper had to be reduced the entire speed of the system had to
be reduced to avoid jamming the system. Additionally, the present
system eliminates or significantly reduces the stack entering
variation into the wrapping arrangement 116. Stack entering
variation forces the wrapping arrangement 116 to stop and start.
However, wrapping arrangements, and particularly progressive
wrapping arrangements, do not readily handle stopping and starting
operation.
[0119] All references, including publications, patent applications,
and patents cited herein are hereby incorporated by reference to
the same extent as if each reference were individually and
specifically indicated to be incorporated by reference and were set
forth in its entirety herein.
[0120] The use of the terms "a" and "an" and "the" and similar
referents in the context of describing the invention (especially in
the context of the following claims) is to be construed to cover
both the singular and the plural, unless otherwise indicated herein
or clearly contradicted by context. The terms "comprising,"
"having," "including," and "containing" are to be construed as
open-ended terms (i.e., meaning "including, but not limited to,")
unless otherwise noted. Recitation of ranges of values herein are
merely intended to serve as a shorthand method of referring
individually to each separate value falling within the range,
unless otherwise indicated herein, and each separate value is
incorporated into the specification as if it were individually
recited herein. All methods described herein can be performed in
any suitable order unless otherwise indicated herein or otherwise
clearly contradicted by context. The use of any and all examples,
or exemplary language (e.g., "such as") provided herein, is
intended merely to better illuminate the invention and does not
pose a limitation on the scope of the invention unless otherwise
claimed. No language in the specification should be construed as
indicating any non-claimed element as essential to the practice of
the invention.
[0121] Preferred embodiments of this invention are described
herein, including the best mode known to the inventors for carrying
out the invention. Variations of those preferred embodiments may
become apparent to those of ordinary skill in the art upon reading
the foregoing description. The inventors expect skilled artisans to
employ such variations as appropriate, and the inventors intend for
the invention to be practiced otherwise than as specifically
described herein. Accordingly, this invention includes all
modifications and equivalents of the subject matter recited in the
claims appended hereto as permitted by applicable law. Moreover,
any combination of the above-described elements in all possible
variations thereof is encompassed by the invention unless otherwise
indicated herein or otherwise clearly contradicted by context.
* * * * *