U.S. patent application number 14/559704 was filed with the patent office on 2016-06-09 for stacked-roller belt conveyor with zone control.
The applicant listed for this patent is Laitram, L.L.C.. Invention is credited to Matthew L. Fourney.
Application Number | 20160159575 14/559704 |
Document ID | / |
Family ID | 56027733 |
Filed Date | 2016-06-09 |
United States Patent
Application |
20160159575 |
Kind Code |
A1 |
Fourney; Matthew L. |
June 9, 2016 |
STACKED-ROLLER BELT CONVEYOR WITH ZONE CONTROL
Abstract
A zone-controlled in-line, stacked-roller conveyor belt. The
belt has pairs of stacked rollers--a top article-supporting roller
and a bottom driven roller. The top and bottom rollers contact each
other so that when the bottom roller is driven in one direction by
contact with a bearing surface under the belt as the belt advances,
the top roller rotates in the opposite direction--opposite to the
direction of belt travel. Articles atop the actuated roller pairs
mark time. When the bottom roller is out of contact with a bearing
surface, the rollers are braked and do not rotate so that the
articles atop the braked rollers advance with the belt. The bearing
surfaces are arranged in individually controllable segments that
are dynamically grouped into zones that are actuated to halt an
article in that zone. An imaging system is used by a controller to
change the zone grouping dynamically.
Inventors: |
Fourney; Matthew L.;
(Laurel, MD) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Laitram, L.L.C. |
Harahan |
LA |
US |
|
|
Family ID: |
56027733 |
Appl. No.: |
14/559704 |
Filed: |
December 3, 2014 |
Current U.S.
Class: |
198/463.1 ;
198/779 |
Current CPC
Class: |
B65G 17/24 20130101;
B65G 17/46 20130101; B65G 39/20 20130101 |
International
Class: |
B65G 17/08 20060101
B65G017/08 |
Claims
1. A conveyor belt comprising: a top side and an opposite bottom
side; multiple roller sets each including: a top roller at the top
side for supporting conveyed articles; a bottom roller at the
bottom side in contact with the top roller such that rotation of
the bottom roller in a first direction causes rotation of the top
roller in an opposite second direction; channels along which the
roller sets are translated from a first position in which the top
roller extends to a maximum level above the top side and a second
position in which the top roller extends to a minimum level below
the maximum level; a braking surface associated with each roller
set and contacting the top roller when the roller set is in the
second position to prevent the top roller from rotating.
2. (canceled)
3. A conveyor belt as in claim 1 wherein the braking surface lies
below the top roller so that the weight of a conveyed article
resting on the top roller pushes the top roller against the braking
surface.
4. A conveyor belt as in claim 1 wherein the multiple rollers sets
are arranged in columns of roller sets extending along the length
of the conveyor belt and rows of roller sets extending across the
width of the conveyor belt.
5. A conveyor belt as in claim 1 wherein the conveyor belt travels
in a direction of belt travel and the top and bottom rollers rotate
on axes perpendicular to the direction of belt travel.
6. A conveyor comprising: a conveyor belt including: a top side and
an opposite bottom side; multiple roller sets each including: a top
roller at the top side for supporting conveyed articles; a bottom
roller at the bottom side in contact with the top roller such that
rotation of the bottom roller in a first direction causes rotation
of the top roller in an opposite second direction; wherein the
roller sets are movable from a first position in which the top
roller extends to a maximum level above the top side and a second
position in which the top roller extends to a minimum level below
the maximum level; an array of independently actuated segments
under the bottom side of the conveyor belt, each segment including
a bearing surface selectively movable into and out of contact with
the bottom rollers; wherein the roller sets are moved into the
first position with the bottom rollers rotating on the bearing
surface when the bearing surface is moved into contact with the
bottom rollers and wherein the roller sets are moved into the
second position when the bearing surface is out of contact with the
bottom rollers.
7. A conveyor as in claim 6 wherein the conveyor belt further
includes a braking surface associated with each roller set and
contacting the top roller when the roller set is in the second
position to prevent the top roller from rotating.
8. A conveyor as in claim 7 wherein the braking surface lies below
the top roller so that the weight of a conveyed article resting on
the top roller pushes the top roller against the braking
surface.
9. A conveyor as in claim 6 wherein the conveyor belt further
includes channels along which the roller sets are moved from the
first position to the second position.
10. A conveyor as in claim 6 wherein the conveyor belt travels in a
direction of belt travel and the top and bottom rollers rotate on
axes perpendicular to the direction of belt travel.
11. A conveyor as in claim 6 further comprising a controller and a
plurality of actuators, each coupled to a respective one on the
segments, wherein the controller groups one or more subsets of the
segments into one or more control zones and sends control signals
to the actuators to either actuate or deactuate all the segments in
each control zone simultaneously.
12. A conveyor as in claim 6 further comprising a controller and an
imaging system producing successive digital images of conveyed
articles atop the conveyor belt, wherein the controller actuates
the segments as a function of the digital images.
13. A method for conveying articles, the method comprising:
supporting articles atop sets of vertically stacked top and bottom
rollers in a conveyor belt advancing in a direction of belt travel;
forming a carryway for the conveyor belt with an array of
individually actuatable bearing surface segments under the conveyor
belt; selectively actuating bearing surface segments to move into a
first position in contact with bottom rollers to raise the top
rollers to a maximum level above the top of the conveyor belt and
to rotate the top rollers in a direction opposite to the direction
of belt travel so that articles atop the rotating top rollers mark
time; selectively deactuating bearing surface segments to move into
a second position out of contact with the bottom rollers to the top
rollers to be lowered to a minimum level below the maximum level;
frictionally braking deactuated top rollers so that articles atop
the braked top rollers advance in the direction of belt travel with
the conveyor belt.
14. The method of claim 13 further comprising: grouping one or more
subsets of the bearing surface segments into one or more control
zones defined by the combined footprints of the bearing surface
segments grouped in the subset; either actuating or deactuating all
the bearing surface segments in each control zone
simultaneously.
15. The method of claim 14 further comprising: imaging the articles
to provide digital images of the articles atop the conveyor belt;
grouping the one or more subsets of the bearing surface segments
into one or more control zones defined by the combined footprints
of the bearing surface segments grouped in the subset as a function
of the digital images.
16. The method of claim 14 further comprising successively
regrouping the bearing surface segments into control zones having
other different footprints as the articles are conveyed to
different positions.
Description
BACKGROUND
[0001] The invention relates generally to power-driven conveyors
and more particularly to belt conveyors with stacked rollers.
[0002] In many conveying applications it is necessary to convert a
mass flow of articles into a single file. For example, some
processing devices can operate on only one article at a time. In
those cases, the articles must be singulated before reaching the
devices. And as another example, the sorting of singulated articles
on a conveyor is simpler if the articles are in a single file
rather than side by side.
SUMMARY
[0003] One version of a conveyor belt embodying features of the
invention comprises multiple roller sets each including a top
roller and a bottom roller. The top roller at the top side of the
conveyor belt supports conveyed articles. The bottom roller at the
bottom side of the belt contacts the top roller such that rotation
of the bottom roller in a first direction causes rotation of the
top roller in an opposite second direction. The roller sets are
translated along channels in the conveyor belt from a first
position to a second position. In the first position the top roller
extends to a maximum level above the top side. In the second
position the top roller extends to a minimum level below the
maximum level.
[0004] One version of a conveyor usable with such a conveyor belt
comprises an array of independently actuated segments under the
bottom side of the conveyor belt. Each segment includes a bearing
surface selectively movable into and out of contact with the bottom
rollers. The roller sets are moved into the first position with the
bottom rollers rotating on the bearing surface when the bearing
surface is moved into contact with the bottom rollers. The roller
sets are moved into the second position when the bearing surface is
out of contact with the bottom rollers.
[0005] In another aspect of the invention, a method for conveying
articles comprises: (a) supporting articles atop sets of vertically
stacked top and bottom rollers in a conveyor belt advancing in a
direction of belt travel; (b) forming a carryway for the conveyor
belt with an array of individually actuatable bearing surface
segments under the conveyor belt; (c) selectively actuating bearing
surface segments to move into a first position in contact with
bottom rollers to raise the top rollers to a maximum level above
the top of the conveyor belt and to rotate the top rollers in a
direction opposite to the direction of belt travel so that articles
atop the rotating top rollers mark time; (d) selectively
deactuating bearing surface segments to move into a second position
out of contact with the bottom rollers to the top rollers to be
lowered to a minimum level below the maximum level; and (e)
frictionally braking deactuated top rollers so that articles atop
the braked top rollers advance in the direction of belt travel with
the conveyor belt.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is an isometric view of a portion of the carryway of
a conveyor embodying features of the invention;
[0007] FIG. 2 is a front elevation view of a portion of the
conveyor of FIG. 1;
[0008] FIG. 3 is a side elevation view of the conveyor of FIG.
1;
[0009] FIG. 4 is a side elevation view of the interior of a
conveyor belt usable in a conveyor as in FIG. 1;
[0010] FIG. 5 is a top plan view of a conveyor system using the
conveyor of FIG. 1; and
[0011] FIG. 6 is a block diagram of a control system usable with
the conveyor system of FIG. 5.
DETAILED DESCRIPTION
[0012] A portion of the carryway of a conveyor system embodying
features of the invention is shown in FIG. 1. The conveyor system
10 includes a modular conveyor belt 11 constructed of a series of
rows 12 of one or more belt modules 14. The rows are linked
together at hinge joints 16 formed by hinge rods 17 linking
interleaved hinge elements 18, 19 of adjacent rows. The conveyor
belt 11 is a dual-roller conveyor belt that includes an array of
roller sets 20 including a top roller 22 and a bottom roller 24
arranged in a vertical stack in a cavity 23 extending from a bottom
side 25 of the belt to a top side 27. The peripheries of the top
and bottom rollers in each set, or stack, are in contact so that
rotation of the bottom roller in one direction causes rotation of
the top roller in the opposite direction. Both the top and bottom
rollers in this example are cylindrical rollers mounted on, or
integrally formed with, axles 26. Because the axles 26 are oriented
perpendicular to the direction of belt travel 28, the rollers
rotate in a direction parallel to the direction of belt travel.
Rollers in this orientation are referred to as in-line rollers
because they rotate in line with the direction of belt travel 26.
The roller sets could alternatively be formed instead with a
spherical roller without an axle in place of the top roller or the
bottom roller. Or each roller set could comprise two top rollers
contacting a single bottom roller, or one top roller contacting a
pair of bottom rollers. The bottom rollers 24 extend down from the
cavity 23 at the bottom side 25 of the belt. The top rollers 22
extend up from the cavity at the top side 27. Alternatively, the
top roller could be supported entirely above the top side, and not
in the cavity, with the bottom roller then extending past both the
bottom and the top sides. The roller sets 20 are arranged in
lateral rows R and longitudinal columns C across the width and
along the length of the belt 11.
[0013] The conveyor carryway includes stationary wearstrips 30
positioned under the top run of the belt 11 between the columns C
of rollers. The remainder of the carryway is divided into
independently controllable bearing surface segments 32 arrayed to
form a grid. Each of the segments is sized, in this example, to
actuate a single roller set 20. But each segment could be larger to
actuate multiple contiguous roller sets. The segments 32 actuate
roller sets 20 by moving into position to contact the bottom
rollers 24 as they pass by. In this example that would mean raising
the segments 32 from the positions shown to a level above the top
bearing surfaces 34 of the wearstrips 30. As the conveyor belt 11
advances in the direction of belt travel 28, the bottom rollers 24
roll on the raised segment's top bearing surface 36. The direction
of rotation of each of the bottom rollers at its top tangent is
parallel to the direction of belt travel 28. With no slip, the
tangential speed of the bottom roller at its top equals the belt
speed. The rolling contact of the bottom roller 24 with the top
roller 22 causes the top roller to rotate in the opposite
direction. The tangential speed of the actuated top roller 22 is
equal to the belt speed, but in the opposite direction. So an
article atop one or more actuated roller sets 20 appears to mark
time--stationary to a stationary observer. This is also shown in
FIG. 3. If the belt travels to the right at a velocity V, the
actuated top rollers 22 have a tangential velocity of --V at the
top. And the absolute velocity of an article 38 atop the actuated
roller sets 20 is zero.
[0014] One scheme for actuating the roller sets 20 is shown in FIG.
2. The roller set 20 on the left is shown actuated. The segment 32
is raised into an actuating position by an actuator 40, such as the
pneumatic or hydraulic cylinder shown, or by cams, motors,
magnetics, or springs, or combinations of those, for example. In
the actuating position, the segment 32 provides a bearing surface
36 on which the bottom roller 24 rolls as the belt advances in the
direction of belt travel. FIG. 3 also shows segments 32 in the
actuating position in contact with the bottom rollers 24. The
segment 32' on the right in FIG. 2 is shown lowered by the actuator
40' to a deactuating position out of contact with the bottom roller
24'. Forward motion of the belt 11 does not impart any rotation to
the deactuated rollers 24', 22' in the roller set 20'.
[0015] As shown in FIG. 3, the axles 26, 27 of the top and bottom
rollers 22, 24 are retained in a long vertical channel 42 at each
end. Or they are retained in a pair of shorter vertical channels
43, 44 at each end. The vertical channels allow the roller sets 20
to move up, when actuated by the segments 24, to an upper, maximum
level 46 shown in FIG. 3 and on the left in FIG. 2 and to move down
to a lower, minimum level 48 shown on the right in FIG. 2. In
addition, as shown in FIG. 4, the deactuated and lowered roller set
40' on the left is frictionally braked because the top roller 22'
is seated on a surface 50 in the belt 11 that acts as a brake pad
to the roller set 20'. The bottom roller 24', out of contact with
the lowered underlying segment, is braked by the braked top roller
22'. The weight of an article atop the deactuated roller set 20'
pushes the top roller 22' downward 52 against the braking surface
50. The braking force is proportional to the weight of the article.
An article atop braked, i.e., deactuated, roller sets 22' travels
with the conveyor belt 11 in the direction of belt travel at the
belt speed.
[0016] When the roller set 20 on the right in FIG. 4 is raised 52
by the underlying segment to the actuated position, the top roller
22 is elevated above the braking surface 50 and rotates as driven
by the bottom roller 24 in contact with the actuated segment.
[0017] Because the actuated top roller 22 in FIG. 2 is elevated to
a higher level 46 than the lower level 48 of the deactuated top
roller 22', articles meant to stay in place along the conveyor run
atop actuated rollers, but extending past the actuated rollers to
deactuated, braked rollers, are not affected by the braked rollers
because the deactuated top rollers are recessed below the level 46
of the actuated roller sets 20 and do not contact the articles. In
the vicinity of lowered, deactuated roller sets 20', the conveyor
belt 11 is supported between the columns of rollers from below by
the stationary wearstrips 32.
[0018] One example of a conveyor system using the conveyor 10 of
FIG. 1 is shown in FIG. 5. The dual-roller conveyor belt 11
advances in the direction of belt travel 28. Individual segments 32
in the array of segments are selectively actuated so as to ensure
that conveyed articles 38 are singulated on a discharge conveyor 54
advancing in a discharge direction 56 perpendicular to the
direction of travel 28 of the dual-roller conveyor belt 11. The
segments 32 are controlled by a controller 58, illustrated in FIG.
6. The controller 58, such as a computer or a programmable logic
controller, for example, receives sensor signals 60 from an optical
or video sensor 62, such as one or more cameras, from a 2D or 3D
laser profiler, or from any sensor capable of acquiring the layouts
of the articles on the conveyor belt. The sensor 62 is positioned
as shown in FIG. 5 to sense the articles 38 on the conveyor belt
11. The controller 58 includes a processor and any processor in the
sensor 62 that is programmed to convert sensor data into digital
images. An imaging algorithm executed by the controller 58 produces
a digital image of the articles on the conveyor belt. The algorithm
runs regularly to produce a succession of images of the articles
showing their positions on the belt and relative to the segments.
The controller 58 executes a control algorithm that groups subsets
of the individual segments 32 into separate control zones 64 for
the articles as a function of the digital image. The size and shape
of each control zone is defined by the combined footprints of the
individual segments that compose that control zone. The controller
then updates the groupings as the conveyor belt advances and the
articles change positions. The control algorithm changes the
control zones 64 dynamically depending on which article or articles
have to move. The zones move and can change shape as the articles
move along the carryway. Segments are dropped from the zones as the
zones move, and new segments are picked up. All the segments in a
control zone 64 at any given time are either actuated (article
halted) or deactuated (article advancing in the direction of belt
travel 28 at the belt speed) by the controller 58. For example, if
the controller determines that the article 38' has to be halted,
the controller defines a control zone 64' comprising segments under
the article. The controller then actuates all those segments
together to actuate the corresponding roller sets in the belt 11.
The article 38' atop the actuated segments in the zone 64' marks
time atop the moving belt 11 to allow another article in a
deactuated zone to pass by or transfer off the end of the belt 11
and onto the discharge conveyor 54. When the controller 58
determines that it's time for the article 38' to advance, the
segments in the control zone 64' are deactuated to brake the roller
sets under the article and allow it to advance with the belt
11.
[0019] As shown in FIG. 6, the controller 58 sends
actuate/deactuate control signals 66A-66N to the actuators 40A-40N
for each segment. The controller 58 can also be used to control
belt speed with a motor control signal 68 to a belt drive motor 70.
The controller can use the belt speed in conjunction with
deactuating and actuating the segments for a finer control of the
delivery of packages. Alternatively, the belt speed can be
separately controlled or can be fixed at a known speed. If the belt
speed is separately controlled and changeable, a speed-indicating
signal could be sent to the controller 58 for use in controlling
the segments 32.
* * * * *