Conveyor system for overcoming the elastic springback in the flaps of an empty box

A conveyor system for retaining a box thereon includes a conveyor assembly slidably adjustable on a frame. The conveyor assembly includes a first set of rollers rotationally mounted on a support rail attached to the conveyor assembly. A corresponding second set of rollers are rotationally mounted to another support rail parallel and spaced apart from the first support rail and fixedly attached to the frame. The rotational axis of each of the rollers is angled forward in the direction of operative travel of the conveyor belt and box. In operation, the angled rollers snugly engage the box and urge the box against the conveyor belt when the box is translated thereby. The distance between the two sets of rollers is adjusted by sliding adjustment of the conveyor assembly with respect to the frame, thus providing for expedited set up of the conveyor system to handle boxes of different widths. A second embodiment is presented wherein the first set of rollers is connected to at least one spring cylinder that biases the first set of rollers toward the second set of rollers.

BACKGROUND OF THE INVENTION 
1. Technical Field 
The invention relates generally to conveyor systems and, more particularly, 
to a conveyor system utilizing angled rollers for retaining an empty box 
on a conveyor belt as the box is transported along the conveyor belt. 
Specifically, the invention relates to a conveyor system that 
automatically adjusts to accommodate unassembled boxes having variations 
in size and delivers the boxes along a common index line and that utilizes 
angled rollers for retaining the boxes on the conveyor belt. 
2. Background Information 
Essentially all commercial goods travel through commerce enclosed in some 
type of packaging. Among the most common types of packaging are boxes 
(also referred to as cartons or cases) of a rectangular solid shape and 
that are typically manufactured of corrugated cardboard. Such boxes are of 
innumerable shapes and sizes suited to the specific needs of the packaging 
application. One such type of carton is a parallelepiped box with 
inward-turned flaps on at least the bottom thereof. 
Unassembled parallelepiped boxes are typically cut from a single sheet of 
material and then formed into a generally tubular configuration having 
four sides. Each side terminates with a top flap and a bottom flap at 
opposite ends thereof. The top flaps and bottom flaps are folded inwardly 
and sealed to form top and bottom sides, respectively. Such boxes are 
typically shipped from a manufacturer in a flat configuration as blanks 
that must be assembled into a three-dimensional box prior to use. Such 
assembly can be by hand or through the use of a box erecting machine. 
The flaps of a box are designated in the art as "major" and "minor" 
depending on their relative length. For instance, in a parallelepiped box 
having a length, a width, and a height, with the length and width being 
unequal, the major flaps are the two opposed flaps lying adjacent the 
longer of the length and width, with the minor flaps being the flaps 
adjacent the shorter of the length and the width. While many 
parallelepiped boxes have bottom-forming flaps and top-forming flaps, some 
parallelepiped boxes have only bottom-forming flaps, with the fully 
assembled box having an open top. 
Parallelepiped boxes are assembled by first drawing the unassembled, flat 
box into a generally tubular rectangular shape. The minor flaps are each 
folded 90 degrees inward, with the major flaps then being folded 90 
degrees inward and over the minor flaps. The flaps may then be sealed in 
place using glue, adhesive tape, gummed tape, or other such materials that 
are known and understood in the relevant art. In some situations, the 
bottom flaps are not sealed until after the box has been filled. 
The bottom flaps of a parallelepiped box often are folded first with the 
top flaps being left open or unassembled so that the box can be filled 
with the appropriate contents. The box filling operation typically occurs 
on an open conveyor system. Such an open conveyor system typically 
includes a conveyor belt on which the boxes travel and sets of rollers on 
either side of the boxes parallel with the direction of belt travel to 
maintain boxes in the proper orientation as they travel down the conveyor 
belt for filling. 
After a box has been filled, the final step is to fold and seal the top 
flaps of the box. The top flaps are assembled in a manner similar to the 
assembly of the bottom flaps, i.e., folding the minor flaps 90 degrees 
inward, folding the major flaps 90 degrees inward and over the minor 
flaps, and then sealing the major flaps in position with glue, adhesive 
tape, gummed tape, or the like. If the bottom flaps have not yet been 
sealed, they will typically be sealed at this point. 
Such operations often are performed as part of an assembly line operation 
with the unfolded boxes being loaded into a magazine, each box being 
opened in turn and the bottom flaps thereof assembled to form a bottom. 
The boxes are then appropriately filled and the flaps thereof assembled. 
When adhesive tape is utilized to seal the flaps of the box, the tape is 
typically delivered from a large roll attached to a tape head of the type 
known and understood in the relevant art. As indicated hereinbefore, the 
bottom flaps of a box may be folded prior to being filled and left 
unsealed until after the box has been filled and the top flaps have been 
folded into place. In such assembly lines, the bottom flaps and the top 
flaps of the boxes are typically sealed simultaneously by taping or gluing 
structures located both above and below the box assembly line. 
One reason, among others, for performing the taping or gluing operations 
simultaneously on both the top and bottom flaps of a box is to facilitate 
replacement of tape rolls, refilling of glue reservoirs, etc., from a 
single location. Inasmuch as the boxes must typically be removed from the 
assembly line prior to replacing a tape roll, the removal of boxes from 
only one portion of the line while replacing the tape rolls on both the 
upper and lower taping mechanisms results in significant savings in cost 
and time. If the taping mechanisms for taping the top flaps and the bottom 
flaps are located at different points along the production line, boxes 
must be removed from both regions of the line to replace the tape rolls at 
those locations, thus requiring the expenditure of additional time and 
effort. 
If the bottom flaps of a box are not sealed prior to being filled, the 
unsealed box typically must be held downward on the conveyor belt by a 
suitable structure, otherwise the combined elastic springback of the four 
bottom flaps will cause the box to rise up off the conveyor belt, often 
resulting in misalignments, jamming, and other conveyance problems. Such 
elastic springback is inherent in most materials, including those used to 
manufacture boxes. The elastic springback in the boxes is preferably 
overcome to assure continuous and reliable box conveyance and to prevent 
the interruptions and downtime to the production line resulting from boxes 
losing contact with the conveyer belt, becoming misaligned, and ultimately 
causing jams and other such problems. The unsealed boxed must be held 
against the conveyer belt prior to filling and must additionally be held 
subsequent to filling if the fill material is light or contains a great 
proportion of lightweight packing material that is of insufficient weight 
to overcome the aforementioned elastic springback. 
One method known in the art of countering the elastic springback inherent 
in the folded but unsealed bottom flaps of a carton is to employ 
forward-angled rollers on either side of the boxes as they travel down the 
conveyor belt. The forward-angled rollers have the tendency to drive the 
box in a downward direction toward the conveyor belt as the box moves 
forward, thus retaining the box on the conveyor belt. Such forward-angled 
rollers have been used in other box-moving conveyor systems wherein it is 
desired to retain a box on a conveyor belt. 
Box erecting machines and box conveyors of the type described above are 
rather complex and expensive machines that are permanently installed in 
production lines and are capable of being set up to assemble and transport 
boxes of different sizes. Such machines typically include adjustable guide 
rails that have rollers to maintain the boxes in proper orientation. 
One such machine utilizes both a stationary guide and an adjustable guide 
that is adjusted to correspond with the width of the box being 
transported. One reason for designing machinery to contain a fixed guide 
and a moveable guide is to permit the boxes, as they are assembled and 
filled, to travel along a fixed, constant "index" line. Inasmuch as the 
cartons are assembled for the purpose of carrying goods, the goods must, 
at some point, be loaded into the boxes. Boxes traveling through a 
production line along a fixed index line are more easily filled than boxes 
that are delivered centered along a conveyor system inasmuch as centered 
boxes require a longer reach by the individual or the machinery that fills 
the box. Boxes traveling along a common index line can be filled directly 
from the index line with minimal reach and minimal wasted effort. 
Additionally, the use of a common index line for the filling of boxes 
expedites the setup of automated machinery used for filling such boxes. 
Such machinery has not, however, utilized forward-angled rollers to retain 
a box on a conveyor belt. 
Another problem associated with erecting boxes in box erecting machines is 
that the standard tolerances of the box industry allow for varying 
dimensions such that each box has slightly varying width, length, and 
height dimensions. Although these varying dimensions do not create 
problems when the box is erected by hand, the varying dimensions can cause 
a box erecting machine to jam. In some boxes the dimensions may vary as 
much as 1/8 of an inch above or below the target dimension for a total of 
1/4 of an inch of uncertainty in the dimension. If the rollers are 
adjusted to the nominal dimension, boxes smaller than the nominal 
dimension may not be held by the rollers, and boxes larger than the 
nominal dimension might jam between the rollers if the rollers are fixed 
and are unable to adjust automatically to accommodate the different sized 
boxes. 
The invention disclosed in U.S. Pat. No. 5,735,378 to Sundquist discloses a 
conveyor system utilizing forward-angled rollers to hold a carton downward 
on a conveyor system as the carton is transported. While the invention 
disclosed in Sundquist has achieved success for the purposes disclosed 
therein, Sundquist does not disclose a carton conveyor system capable of 
delivering boxes of different sizes along a common index line and does not 
disclose a conveyor system that can automatically adjust to accommodate 
boxes having dimensional variations. 
Thus, a need exists for a conveyor system that can retaining an empty box 
on a conveyor belt along a common index line, that can automatically 
adjust to accommodate the dimensional variations of boxes, and that can 
function cooperatively with other box erecting and box taping machines 
which utilize a common index line and which are known and understood in 
the relevant art. 
SUMMARY OF THE INVENTION 
In view of the foregoing, an objective of the present invention is to 
provide a conveyor system that can overcome the elastic springback 
inherent in the folded but unsealed bottom flaps of a box. 
Another objective of the present invention is to provide a conveyor system 
that can retain an empty box on a conveyor belt. 
Another objective of the present invention is to provide a conveyor system 
that utilizes forward-angled rollers to retain an empty box on a conveyor 
belt. 
Another objective of the present invention is to provide a conveyor system 
that can deliver boxes of different sizes along a common index line. 
Another objective of the present invention is to provide a conveyor system 
utilizing forward-angled rollers to retain a box on a conveyor belt and 
that is readily adjustable for use with boxes of different sizes. 
Another objective of the present invention is to provide a conveyor system 
having a set of forward-angled rollers rotationally mounted on an 
adjustable support rail. 
Another objective of the present invention is to provide a conveyor system 
that can transport folded but unsealed boxes. 
Another objective of the present invention is to provide a conveyor system 
that can transport empty boxes and minimize the potential for jamming and 
other conveyance problems. 
Another objective of the present invention is to provide a conveyor system 
that can cooperate functionally with box erecting and sealing machines 
known and understood in the relevant art. 
Another objective of the present invention is to provide a conveyor system 
that can overcome the elastic springback inherent in folded but unsealed 
bottom flaps of boxes to reliably transport empty or lightly loaded boxes. 
Another objective of the present invention is to provide a conveyor system 
having at least one spring-loaded rail that includes a plurality of 
forward-angled rollers. 
Another objective of the present invention is to provide a conveyor system 
having two sets of forward-angled rollers that can automatically adjust to 
accommodate boxes having variations in size. 
Another objective of the present invention is to provide a conveyor system 
that can be adjusted to a nominal position and additionally includes a 
self-adjusting mechanism that allows the conveyor system to accommodate 
boxes having dimensional variations. 
Another objective of the present invention is to provide a conveyor system 
having a spring-loaded guide rail while delivering boxes along a common 
index line. 
Another objective of the present invention is to provide a conveyor system 
that can transport boxes having nominal dimensional variations without the 
dimensional variations causing conveyance problems such as jamming and 
misalignment, as well as other conveyance problems. 
A further objective of the present invention is to provide a conveyor 
system that facilitates proper adjustment of the conveyor system by 
automatically providing and taking up slack as needed. 
These and other objectives and advantages of the invention are obtained 
from the conveyor system for retaining an empty box invention, the general 
nature of which can be stated as including a frame, a plurality of first 
angled rollers rotatably mounted on the frame, a conveyor assembly 
adjustably mounted on the frame, at least a first spring mounted on the 
conveyor assembly, a movable support rail adjustably mounted on the at 
least first spring , a plurality of second angled rollers rotatably 
mounted on the movable support rail, the second angled rollers biased by 
the spring toward the first angled rollers, and a conveyer belt disposed 
at least partially between the first angled rollers and the movable 
support rail. 
Other objectives and advantages are obtained from the improvement of the 
present invention, the general nature of which can be stated as relating 
to a conveyor system of the type having a frame, a plurality of first 
angled rollers rotatably mounted on the frame, a movable support rail 
adjustably mounted on the frame, a plurality of said second angled rollers 
rotatably mounted on the movable support rail, and a conveyor belt 
disposed at least partially between the first angled rollers and the 
movable support rail, the improvement comprising at least a first spring 
adjustably mounted on the frame and the movable support rail mounted on 
the at least first spring. 
Still other objectives and advantages are obtained from the conveyor system 
of the present invention, the general nature of which can be stated as 
including a frame, a plurality of first angled rollers rotatably mounted 
on the frame, a conveyor assembly adjustably mounted on the frame, a 
movable support rail mounted on the conveyor assembly, a plurality of 
second angled rollers rotatably mounted on the movable support rail, a 
first conveyor belt disposed at least partially between the first angled 
rollers and the movable support rail, and biasing means for biasing the 
movable support rail toward the first angled rollers such that the movable 
support rail automatically adjusts to accommodate the box on the conveyor 
belt and the first and second angled rollers maintain a retention force on 
the box.

Similar numerals refer to similar parts throughout the specification. 
DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The conveyor system of the present invention is indicated generally by the 
numeral 2 in the accompanying drawings. Conveyor system 2 includes a frame 
4 upon which is mounted a conveyor assembly 6. Conveyor assembly 6 
includes a conveyor frame 8 about which is driven a conveyor belt 10. 
Conveyor belt 10 is a conventional conveyor belt known and understood in 
the relevant art. Conveyor belt 10 is driven by a drive motor 12 that is 
operatively connected with conveyor belt 10 by a belt 14. In the other 
embodiments of the present invention, conveyor assembly 6 may include a 
plurality of powered rollers instead in place of conveyor belt 10 or other 
similar conveying devices other than belt 10. 
Conveyor assembly 6 is slidably mounted on frame 4 by the sliding 
engagement of a pair of bars 16 attached to conveyor assembly 6 with a 
corresponding pair of saddles 20 attached to frame 4. Bars 16 are mounted 
transverse to the operative direction of movement of conveyer belt 10. As 
best shown in FIG. 7, each bar 16 is an elongated body containing a pair 
of indentations 18 on opposite sides of bar 16 and extending the length 
thereof. Each saddle 20 has a channel 22 of a cross section corresponding 
with that of bar 16. As can be seen in FIG. 7, each saddle 20 contains a 
pair of dimples 24 on opposite sides of channel 22 and extending the 
length thereof. The cross section of bar 16 corresponds with the cross 
section of channel 22, and dimples 24 correspond with indentations 18 such 
that bar 16 is slidably mounted within channel 22 of saddle 20. In 
accordance with the objectives of the invention, and as seen in FIG. 7, 
the cooperation of indentations 18 with dimples 24 permits bar 16 to slide 
within channel 22, yet prevents substantially any movement of bar 16 in a 
direction other than longitudinal with respect to the length of bar 16. In 
accordance with the features of the present invention, the interaction of 
indentations 18 with dimples 24 enhances the structural stability of 
conveyor system 2 by maintaining conveyor assembly 6 in a substantially 
stable, planar relationship with frame 4. 
Conveyor assembly 6 is slidably adjusted with respect to frame 4 by 
operation of a threaded adjustment crank 26 rotationally mounted on 
conveyor assembly 6 and threadedly connected with a threaded block 28 
attached to frame 4. In accordance with the objectives of the present 
invention, and as shown in FIG. 5, the selective rotation of adjustment 
crank 26, with the corresponding threaded interaction of adjustment crank 
26 with block 28, causes conveyor assembly 6 to move slidably between 
inward and outward positions with respect to frame 4. In other embodiments 
of the present invention, threaded block 28 may be attached to conveyor 
assembly 6 with adjustment crank 26 rotationally mounted on frame 4. 
In accordance with the objectives of the invention, a first set of rollers 
30 is rotationally mounted to a movable support rail 32 fixedly attached 
to conveyor frame 8. A corresponding second set of rollers 34 is 
rotationally mounted to a fixed support rail 36 which is, in turn, fixedly 
attached to frame 4. An index line 44 is defined along a reference plane 
extending upwardly from the outermost edges of rollers 34 facing rollers 
30. Rails 32 and 36 are preferably parallel and spaced apart. 
Each roller 30 and 34 is of a type known and understood in the art for the 
purpose of engaging a cardboard box. Rollers 30 and 34 are preferably of a 
durable rubber-type compound, although other materials and compounds may 
be used for the manufacture of rollers 30 and 34 without departing from 
the spirit of the present invention. 
As can be seen in FIG. 6, rollers 30 and 34 are axially mounted to rails 32 
and 36, respectively, and the axis of rotation of rollers 30 and 34 is 
angled from vertical. FIG. 6 depicts a box 38 and an arrow, indicated by 
the letter A, indicating the travel direction of box 38 as it is 
transported by conveyor belt 10. The rotational axis of each of rollers 30 
and 34 is angled forward in the direction of arrow A at an angle in the 
range of approximately 10.degree. to 30.degree., although angles greater 
and lesser may be used without departing from the spirit of the present 
invention. The rotational axis of each of rollers 30 and 34 is preferably 
the same such that each of rollers 30 and 34 rotate about axes that are 
parallel and spaced apart. The forward rotational alignment of rollers 30 
and 34 causes box 38 to be driven against conveyor belt 10 as box 38 is 
translated by conveyor belt 10. 
In use, adjustment crank 26 is turned until box 38 fits snugly between 
rollers 30 and rollers 34. As is known and understood in the relevant art, 
rollers 30 and 34 have at least a nominal resilient character. Moreover, 
as can be seen in FIG. 4, movable support rail 32 includes a vertical 
member 39 between its point of attachment with conveyor frame 8 and the 
mount for each of rollers 30. Vertical member 39 may be configured or 
designed to possess its own resilient character. Fixed support rail 36 may 
also be configured to possess its own resilient character. 
In accordance with the objectives of the present invention, with rollers 30 
and 34 snugly contacting box 38, the forward motion of conveyor belt 10 in 
the direction of arrow A (FIG. 6) causes rollers 30 and 34 to rotate about 
their respective axes, thus driving box 38 against conveyor belt 10 in a 
manner known and understood in the relevant art. As such, rollers 30 and 
34 have a sliding contact with box 38 and provide a constant downward 
force on box 38 against conveyor belt 10. 
The retention of box 38 on conveyor belt 10 by rollers 30 and 34 provides a 
number of advantages. For example, as is shown in FIG. 4, box 38 contains 
a set of upper flaps 40 and a set of lower flaps 42. Upper flaps 40 are 
unfolded, and lower flaps 42 are shown to be folded but not sealed. In the 
absence of rollers 30 and 34, the elastic springback inherent in lower 
flaps 42 would likely cause empty box 38 to be pushed away from conveyer 
belt 10 and out of proper alignment between rails 32 and 36, thus 
resulting in jams and other conveyance problems. Rollers 30 and 34 thus 
overcome the problems known in the art associated with the elastic 
springback inherent in box flaps. Rollers 30 and 34 retain empty and 
lightly loaded boxes against conveyer belt 10 and overcome the elastic 
springback inherent therein. Even if lower flaps 42 of box 38 are sealed 
in place, rollers 30 and 34 still assist in retaining box 38 against 
conveyor belt 10, thus inhibiting jams and other such conveyance problems 
inherent in the conveyance of boxes. 
As can be seen in FIG. 4, conveyor belt 10 is positioned substantially 
between rollers 30 and rollers 34, although conveyor belt 10 is not 
centered therebetween. Box 38, as shown in FIG. 4, extends a certain 
distance beyond the edge of conveyor belt 10 before it contacts rollers 
34. Such overlap is irrelevant to the present invention inasmuch as 
rollers 30 and 34 urge box 38 against conveyor belt 10. Similarly, rollers 
30 and rollers 34 are depicted in the accompanying drawings as being at 
different heights with regard to conveyor belt 10. Again, such height 
differential does not interfere with the proper functioning of the present 
invention, and rather enhances the versatility thereof by permitting 
conveyor system 2 to accommodate boxes of a wide variety of sizes. 
In accordance with the objectives of the present invention, and as can be 
seen in FIG. 5, rollers 30 are each mounted to rail 32 which is, in turn, 
attached to conveyor assembly 6. Thus, adjustment of conveyor assembly 6 
by rotation of adjustment crank 26 causes rollers 30 to simultaneously 
move inwardly and outwardly as desired. The simplified adjustment inward 
and outward of rollers 30 with respect to roller 34 permits conveyor 
system 2 to be quickly adjusted to accommodate boxes of different widths. 
The expedited setup of conveyor system 2 results in significant savings in 
cost and time beyond that provided by devices previously known and 
understood in the relevant art. 
In accordance with the features of the invention, box 38 travels against 
index line 44 at it is moved by conveyer belt 10. As indicated 
hereinbefore, the use of an index line in a conveyer system is known in 
the packaging arts to provide significant benefits in time, effort, and 
cost. Index line 44 of conveyer system 2 can be aligned with the index 
lines of other devices known in the art such the box erecting machine 50 
and the taping machine 52, depicted in FIG. 1, to create a common index 
line shared with all of the packaging machinery in a production line. 
Conveyer system 2 can work with other packaging machinery known in the art 
and can be easily incorporated into an assembly line therewith, thus 
providing substantial benefits to the user. The configuration depicted in 
FIG. 1 allows boxes to be erected from blanks in apparatus 50 and then 
ejected onto conveyor system 2 of the present invention where the boxes 
are loaded by workers or by automated machinery. Conveyor system 2 holds 
the empty boxes in the proper position until they are loaded and then 
maintains their proper alignment until they are fed into taping machine 52 
where the bottom and top of each box is appropriately sealed. Each machine 
50 and 52 typically has a fixed index line where all adjustments are taken 
from. The index line of conveyor system 2 allows it to be readily fit 
between machines 50 and 52 and adjusted in a similar manner. 
A second embodiment of the conveyor system of the present invention is 
indicated generally by the numeral 102 in FIGS. 8-11. Conveyor system 102 
is similar to conveyor system 2 except that support rail 32 of conveyor 
system 102 is not fixedly attached to conveyor frame 8 but rather has a 
spring-loaded attachment to conveyor assembly 6. Specifically, support 
rail 32 is fixedly attached to four spring cylinders 150 that are mounted 
on a pair of T-shaped posts 152. Posts 152 each protrude upwardly from and 
are fixedly attached to a member 153 that extends from conveyor assembly 
6. 
Each spring cylinder 150 includes a barrel 154, a plunger 156, and a spring 
158. Barrel 154 is an elongated body formed with a substantially 
cylindrical cavity 160 that terminates internally at a substantially flat 
stop 162. Barrel 154 is additionally formed with a longitudinally oriented 
slot 164 extending between cavity 160 and the outer surface of barrel 154. 
Plunger 156 is an elongated body of substantially circular cross section 
configured to be slidingly received within cavity 160 and long enough to 
allow an end thereof to protrude from barrel 154. The protruding end of 
plunger 156 is formed with a threaded hole 166 that threadably receives a 
bolt 168 therein. Bolt 168 threadably and fixedly attaches support rail 32 
to plunger 156. Plunger 156 additionally includes a post 170 disposed 
therein across a diameter of plunger 156 and protruding therefrom. As is 
best shown in FIG. 11, the shaft of post 170 protrudes outwardly from 
plunger 156 and extends into slot 164. 
Spring 158 is interposed between stop 162 and plunger 156 inside cavity 
160. Spring 158 biases support rail 32 and rollers 30 against box 38 and 
maintains a retention force between rollers 30 and 34 and box 38. The 
retention force ensures that rollers 30 and 34 remain in contact with box 
38 to hold box 38 downward against conveyor belt 10. Slot 164 frictionally 
engages post 170 and serves as a stop that limits the outward extension of 
plunger 156 when no box is present between rails 32 and 36. In the 
preferred embodiments, post 170 is a screw that is threaded into plunger 
156, but may be essentially any other structure that protrudes outwardly 
from plunger 156 through slot 164 without departing from the spirit of the 
present invention. Inasmuch as spring cylinders 150 bias support rail 130 
in the direction of rollers 30, it is understood that a variety of other 
biasing structures could be used in place of spring 152 or spring cylinder 
150, such as leaf springs, resilient rubber members, gas filled cylinders, 
etc., without departing from the spirit of the present invention. 
As is best shown in FIG. 9, each of posts 152 carries a pair of spring 
cylinders 150 to ensure that support rail 32 is supported sufficiently in 
the vertical direction. Barrels 154 are each fixedly attached to a post 
152, with posts 152 each, in turn, mounted on one of members 153. 
As is best shown in FIG. 11, plunger 156 is slidingly received in cavity 
160 of barrel 154. In operation, adjustment crank 26 is adjusted until 
rollers 30 are at least nominally compressed against box 38. Inasmuch as 
spring cylinders 150 permit support rail 32 to move toward and away from 
rollers 30 in response to different sized boxes, it is preferred that 
adjustment crank 26 be adjusted until screws 170 are substantially 
centered within slots 164. 
When an oversize box 38 is conveyed by conveyor system 2, plunger 156 will 
slidably extend farther into cavity 160, thus providing rollers 30 with 
sufficient slack to allow the oversize box 38 to pass between rollers 30 
and 34 without jamming or other conveyance problems. Similarly, when an 
undersized box is transported between rollers 30 and 34, spring 158 biases 
plunger 156 outwardly from barrel 154, thus taking up the slack that would 
otherwise develop between the undersized box and rollers 30 and 34. In 
this regard, inasmuch as the variance in box sizes can be as large as one 
quarter inch, it is preferred that slot 164 be at least one quarter of an 
inch in length, and preferably be at least one half inch with spring 158, 
barrel 154, and plunger 156 configured accordingly. It is understood, 
however, that slots 164 can be of lengths shorter and longer without 
departing from the spirit of the present invention. 
In accordance with the features of the present invention, the spring 
loading of support rail 32 permits conveyor system 102 to convey boxes 38 
having nominal size differences without the differences in size creating 
conveyance problems such as jamming, misalignment, etc. Further in 
accordance with the objectives of the present invention, the inclusion of 
spring cylinder 150 permits the proper adjustment of conveyor assembly 6 
to be less critical inasmuch as spring 158 permits support rail 32 to take 
up and provide slack as needed between rollers 30 and box 38. 
Accordingly, the improved conveyor system for retaining an empty box 
invention is simplified, provides an effective, safe, inexpensive, and 
efficient device which achieves all the enumerated objectives, provides 
for eliminating difficulties encountered with prior devices, and solves 
problems and obtains new results in the art. 
In the foregoing description, certain terms have been used for brevity, 
clearness, and understanding; but no unnecessary limitations are to be 
implied therefrom beyond the requirement of the prior art, because such 
terms are used for descriptive purposes and are intended to be broadly 
construed. 
Moreover, the description and illustration of the invention is by way of 
example, and the scope of the invention is not limited to the exact 
details shown or described. 
Having now described the features, discoveries, and principles of the 
invention, the manner in which the conveyor system for retaining an empty 
box invention is constructed and used, the characteristics of the 
construction, and the advantageous new and useful results obtained; the 
new and useful structures, devices, elements, arrangements, parts, and 
combinations are set forth in the appended claims.