Method and apparatus for feeding sheets

A feeder for feeding corrugated blanks in a box finishing machine including overlying and underlying endless timing belts sandwiching the blanks to feed them. The belts are spaced from each other to form a first gap at rectilinearly moving sections located between opposite end pulleys of the belts. The gap between the belts at the inlet and outlet pulleys is greater than the first gap whereby blanks are engaged and fed by the belt sections as they move rectilinearly between the opposite end pulleys. One of the belts is urged into yieldable engagement with the blank by a pressure mechanism including a floating pressure plate engaging the belt and a spring engaging the pressure plate. An extended stroke feeder is used to feed blanks to the endless belts at a constant velocity matched to the velocity of the belts.

BACKGROUND OF INVENTION 
The present invention generally relates to conveying or feeding sheets or 
sheet material such as, for example, corrugated blanks, in a box finishing 
machine. In such machine it is important that the sheets are fed in 
synchronism with the operations performed at the stations along the 
machine, such operations being, for example, printing, slotting and 
scoring, folding and gluing. In the box finishing machine art, synchronous 
feeding of the sheets relative to the cycle of operation at the various 
stations along the machine is often referred to as "register feeding" or 
"feeding in register". In order for the operations such as printing, 
slotting, scoring, folding and gluing to be performed at the right 
locations on the sheet, it is obvious that the sheet must arrive at the 
stations at precisely the right times. 
In a box finishing machine, for example, corrugated blanks are fed from a 
vertical hopper one by one from beneath the hopper by means of a first 
feeder which sequentially transports the blanks from the bottom of the 
hopper to a second feeder positioned at the beginning or inlet of the box 
finishing machine. In conventional machines, the second feeder may be nip 
rolls or feed rolls. In the corrugated box art, the second feeder could be 
termed a transfer conveyor, pull conveyor or feeder conveyor. 
Feed rolls or nip rolls include an underlying roll typically having a 
knurled steel surface and an upper roll having for example a steel core 
and a grooved rubber surface layer. The sheet or corrugated blank being 
fed is of course gripped between the rolls and fed along the path of the 
finishing machine. The area of contact with the corrugated blank is 
limited to that which occurs at the nip of the feed rolls. Consequently, 
it is necessary to provide sufficient force at the nip to ensure proper 
gripping of the corrugated blank. The result is that the blank being fed 
is susceptible to crushing or deformation, and furthermore it will not be 
gripped with sufficient force if the gap between the rollers is not set to 
precise dimension. Moreover, the precise setting of the gap is not 
predictable with such rolls. In addition, the deformation of the flexible 
or deformable feed roll surfaces causes variation in surface speed 
resulting in loss of register and roll wear. 
More recently a vacuum type conveyor has been used in which for example a 
wheel or belt conveyor is contained in a vacuum box so that the vacuum 
holds the sheet or blank on the belt or wheels of the conveyor. However, 
the problem with this method is that if the vacuum in the vacuum box is 
constant, large air losses occur in the spaces between successive sheets 
or blanks being fed thus requiring a very large volume of air movement and 
vacuum source, not to mention the noise and power requirements that attend 
such installations. 
In an attempt to overcome this problem, application of the vacuum is timed 
with the flow of the sheets or blanks. However this imposes a limitation 
on the speed of the feeding process and in turn production while further 
requiring complicated and expensive mechanisms in order to effect the 
periodic application of vacuum in timed relationship with the flow of 
sheets or blanks. In addition, with a vacuum system, the amount of vacuum 
that can be applied to the sheets is limited and thus loss of register can 
result. 
Another attempt to improve feeding in this art is disclosed in my U.S. Pat. 
No. 5,183,251. While the conveyor disclosed there has advantages over nip 
rolls and vacuum conveyor, it involves the handling of positive air flow 
to hold the blank on the conveyor belt. The flow of air can result in 
problems with dust in downstream operation of printing. 
OBJECTS OF THE PRESENT INVENTION 
One of the objects of the present invention is to provide novel and 
improved method and apparatus for feeding sheets or blanks including 
without limitation corrugated board in a box finishing machine while at 
the same time reducing, if not eliminating, the problems mentioned above 
attendant to conventional feeder systems of the prior art. Although the 
present invention is particularly suitable for use in feeding sheets or 
blanks in a box finishing machine, it will be understood that the present 
invention may have equal applicability for feeding sheets in other 
environments and for other purposes. 
Another object of the present invention is to provide novel and improved 
method and apparatus for feeding corrugated blanks in register in a box 
finishing machine. Included herein are such method and apparatus which may 
use to advantage the EXTEND-O-FEEDtm feeder presently used in industry to 
feed corrugated blanks from a hopper to the inlet of a box finishing 
machine; such a feeder being disclosed in U.S. Pat. No. 5,184,811. 
A further object of the present invention is to provide novel and improved 
method and apparatus for feeding sheets or corrugated boards while 
minimizing if not avoiding crushing of the sheets or boards. Included 
herein are such methods and apparatus which engage the boards over a 
relatively large area requiring less mechanical pressure (p.s.i.) than is 
required with the use of conventional feed or nip rolls. 
Another object of the present invention is to provide a feeder for a box 
finishing machine whose transport speed can be accurately determined and 
maintained to ensure register feeding, 
A still further object of the present invention is to provide novel method 
and apparatus for feeding corrugated board and which will automatically 
adjust to correct operator error or to variations in the contour of the 
board to make certain the board is gripped with proper force for feeding 
but without crushing the board. 
A further object of the present invention is to provide a novel and 
improved sheet feeder which will attain the above objects and yet may be 
incorporated into a conventional box finishing machine. 
A still further object is to provide method and apparatus for feeding 
corrugated board through the use of mechanical pressure thereby avoiding 
the above-noted problems attendant vacuum feeders. 
SUMMARY OF PREFERRED EMBODIMENT OF THE INVENTION 
In summary the present invention, in its preferred embodiment, utilizes 
overlying and underlying endless belts provided by timing belts also known 
as gear belts or synchronous belts. The belts receive the corrugated board 
therebetween in "sandwich" fashion. The gap between the belts at locations 
intermediate their ends when the belts move rectilinearly is less than at 
their ends where the belts are traveling about the pulleys. The boards are 
therefore engaged only at their sections which are moving rectilinearly 
and whose speed can be accurately determined. In the preferred embodiment, 
a pressure means is provided on at least one of the belts intermediate the 
ends thereof for applying and distributing pressure to the board 
throughout a relatively large area limited only by the width and length of 
the belt between centers of the end pulleys. In addition, the preferred 
embodiment has a yieldable biasing means preferably a spring engaging a 
pressure member for urging the belt against the board. 
When used in a box finishing machine, it is preferred that an extended 
stroke feeder such as that disclosed in my parent application identified 
above be used to deliver boards from the hopper to the endless timing 
belts. Such a feeder is capable of feeding the board sufficient distance 
at constant velocity matched to the timing belts to allow the board to be 
fed at such velocity until it reaches the downstream end of the belt 
sections which engage the board.

DETAILED DESCRIPTION 
Referring now to the drawings in detail and initially to FIG. 1 there is 
shown in schematic form a box finishing machine which typically exists in 
the prior art. Such machine includes at the inlet end 12, a feeding 
station where sheets or corrugated boards or blanks are fed from a hopper 
to a pair of nip rolls or feed rolls 24 and 26 as described above under 
the section BACKGROUND OF INVENTION. The hopper and the feeder which 
conveys the blanks from the hopper to the rolls 24 and 26 are not shown in 
FIG. 1, however, corresponding components are shown in FIG. 2 in 
connection with the present invention. Feeder generally designated 30 in 
FIG. 2 is an extended stroke feeder similar to that disclosed in my 
above-identified copending parent application Ser. No. 07/662,034 and U.S. 
Pat. No. 5,184,811, the disclosures of which are hereby incorporated by 
reference into the subject application as part hereof. 
Referring to FIG. 1, the sheets are fed by rolls 24 and 26 to a printing 
station 14 where one or more printing rollers 22 print indicia on the 
sheet after which the sheet is conveyed by pull rolls 23 to further 
stations including slotting and scoring station 16 where the sheet is 
slotted and scored in a predetermined pattern. The sheet is then conveyed 
to a rescoring and gluing station 18 after which the sheet is conveyed to 
a folding station 20 where the sheet is folded so that the glue flap along 
one edge of the sheet is in contact with the opposite edge so as to form a 
folded paper board, cardboard or corrugated board box. 
Referring now to FIGS. 2 and 3, there is shown one preferred embodiment of 
a conveyor system or feeder generally designated 28 in accordance with the 
present invention for feeding sheets or corrugated blanks B along a 
horizontal path in a machine such as a box finishing machine described 
above. Feeder 28 may be used to replace the feed rolls 24 and 26 in a box 
finishing machine such as for example described above in FIG. 1. 
The corrugated blanks B also referred to in the art as boards are stacked 
in a hopper from where they are fed one by one under a gate 34 to the 
feeder 28 by means of an EXTEND-O-FEEDtm conveyor generally designated 30 
which has the capability of feeding the blanks B at a constant velocity 
for an extended stroke or distance sufficient to feed the board B through 
feed belts of the conveyor 28 to be described further below. FIG. 2 also 
shows a trail support 4 and a side guide 5 which guides the boards B as 
they are fed. Feeder 30 includes a plurality of rows of feed rolls 36 and 
38 having a high coefficient friction surface which engage the underside 
of the board to accelerate the board to a velocity matched to the velocity 
of the drive members or belts of feeder 28 and to maintain that matched 
velocity for a time sufficient to feed the board through the feeder 28 as 
will be described. At the conclusion of a feeding cycle, the board B is 
disengaged first from the feed rolls 36 and then from the feed rolls 38 in 
sequential fashion by means of vertically reciprocable grate mechanisms 42 
and 44. The latter are raised and lowered by means of rocker arms 42a and 
44a actuated by rocker shafts 43 and 45 which in turn are actuated by cams 
(not shown). For a more detailed description of the actuation of the 
grates 42 and 44 and the feed rolls 36 and 38, reference may be had to the 
parent patent application Ser. No. 07/257,063 and/or U.S. Pat. No. 
5,184,811, identified above. It should be noted, however, that while the 
sequential disengagement of the feed rolls 36 and 38 is not disclosed in 
the aforementioned application and patent, the principle of operation and 
the components are essentially the same. In the preferred embodiment shown 
in FIG. 2, the sequential disengagement of the boards by the feed rolls 36 
and 38 allows shorter boards to be utilized without effecting the feeding 
since the disengagement of feed rolls 36 will prevent them from contacting 
the board above the board being fed when relatively short boards are being 
fed. It should be understood that a single grate system as disclosed in my 
aforementioned U.S. Pat. No. 5,184,811 may be used in place of the 
multiple grates shown and described herein. FIGS. 2 and 3 also show the 
vacuum box generally designated 40 in which the feed rolls 36, 38 are 
located, all as described in the aforementioned parent application and 
patent. 
In accordance with the present invention, the feeder 28 is used to replace 
the conventional nip rolls, for example, 24 and 26 disclosed in FIG. 1, to 
receive the boards from feeder 30 and to feed the boards to a station 
downstream in the box finishing machine, such station could be, for 
example, 14 shown in FIG. 1 where the blanks are printed with indicia. In 
the preferred embodiment shown, feeder 28 includes overlying and 
underlying endless belts generally designated 50 and 52 trained about 
inlet pulleys 56 and 58 and outlet pulleys 54 and 57, respectively. The 
inlet pulleys 56, 58 are, of course, at the inlet to the feeder 28 through 
which the boards B will sequentially pass. 
In accordance with one of the features of the present invention, endless 
belts 50 and 52 are timing belts also referred to as "gear belts" or 
"synchronous belts". Such belts are characterized in that on their inner 
surface are formed at intermittent locations, transverse grooves 50a and 
teeth 50b throughout the entire endless length of the belts, see FIG. 4 
for the grooves 50a and teeth 50b. The lead and trail pulleys are formed 
about their entire circumference with grooves and teeth complimentary to 
the grooves 50a and teeth 50b of the timing belts, see FIG. 4 where the 
teeth on the pulley 54 is shown at 54a and the grooves at 54b. The grooves 
of the belts, of course, receive the teeth of the pulleys in complementary 
fashion so that upon rotation of the pulleys, the belts will be driven 
along an endless path during which the belts angularly move about the 
pulleys and then rectilinearly between the pulleys as is of course 
well-known. The belts themselves are formed with an outer surface of a 
high coefficient of friction material such as for example urethane as are 
the feed rolls 36, 38 of feeder 30. Typically, the outer layer 50c, 52c of 
such belts are formed of softer material, i.e., rubber or soft urethane, 
than the inner layer 50d, 52d (see FIG. 4). 
Referring to FIGS. 2 and 4, endless belts 50 and 52 are placed in 
overlying, underlying relationship to form therebetween a gap G1 for 
receiving and engaging the boards B with the surfaces of the belts 50 and 
52 to drive the boards downstream to the next station in the box finishing 
machine. The vertical dimension of the gap G1 is determined by pressure 
and/or guide means which in the preferred embodiment include overlying 
upper and underlying lower members 60 and 62 respectively which will be 
termed herein "pressure members", located and engaging the inner surfaces 
of upper belt 50 and lower belt 52 as best shown in FIG. 4. Pressure 
members 60 and 62 may also be termed "slider beds" as the belts 50 and 52 
slide on them during operation. Pressure members 60 and 62 are formed from 
any suitable material such as, for example, aluminum plates and in the 
preferred embodiment extend generally coextensively with sections of the 
belt between the inlet and outlet pulleys. Further, it is preferred that 
the width of the belts 50 and 52 be generally equal to the width of the 
inlet and outlet pulleys. Plates 60 and 62 thus provide rectangular 
pressure distribution surfaces which distribute forces throughout the 
sections of the belt engaged by them. This allows the pressure on the 
boards to be reduced since forces are being distributed over a greater 
area of the belts and consequently crushing of the board is reduced or 
entirely eliminated. 
Pressure members 60 and 62 are set to provide a predetermined gap G1 for 
engaging and feeding the boards B with the belts 50 and 52 but only at 
sections intermediate the inlet and outlet pulleys where the belts are 
moving rectilinearly that is, along straight lines, rather than about the 
inlet and outlet pulleys. Gap G1 is designed to be less in vertical 
dimension than the gap G2 formed at the inlet end of feeder 28 between the 
inlet pulleys 56 and 58 and at the outlet between pulleys 54 and 57. The 
pressure plates 60 and 62 and the inlet pulleys are arranged so that gap 
G2 between the inlet pulleys is greater than gap G1 and also slightly 
greater than the thickness of the boards B being fed. Gap G2 is such that 
the boards B entering the feeder 28 at gap G2 will not be engaged by belts 
50 and 52 and that it is only when the boards enter gap G1 that they will 
be initially engaged by the overlying and underlying belts 50 and 52. Gap 
G1 is set so that the boards will be sufficiently engaged by the 
rectilinearly moving sections of belts 50 and 52 to drive them to the next 
station in the box finishing machine. It is preferred that such engagement 
applies a gripping force to the board generally equal to that of the nip 
rolls 24 and 26 which were used in the prior art and are now replaced by 
feeder 28. In the preferred form of the present invention, feeder 30 
described above is designed to feed the boards B at constant velocity 
matched to the velocity of belts 50 and 52 for a sufficient distance and 
until the boards reach the downstream end of the pressure members 60 and 
62 where the gap changes from G1 to G2. At that point, disengagement of 
the boards B by the feed rolls 38 of feeder 30 may be effected. However, 
the boards B continue to be fed by belts 50 and 52 of feeder 28 to the 
next station downstream in register. In other embodiments of the 
invention, the feeder 28 may continue to feed in conjunction with feeder 
30 beyond the point where the gap changes from G1 to G2. Moreover, when 
feeding shorter length boards B, disengagement may occur approximately 
midway (measured along the direction of travel) of the slider beds 60 and 
62 since less pressure is required to continue feeding such boards. 
In the preferred embodiment upper pressure member 60 is biased, preferably 
by spring mechanisms, against its associated belt 50 to apply sufficient 
pressure to the boards B for feeding. In the specific form shown, the 
spring mechanisms include a plurality of studs 73 respectively threaded 
into apertures in pressure member 60 for receiving compression springs 74 
as best shown in FIG. 4. Studs 73 extend through passages 76 formed in an 
anchor plate 72 overlying pressure member 60 and secured to a support 68 
such as by screws not shown in FIG. 4. Studs 73 are provided with 
shoulders 75 for receiving one of the ends of the compression springs 74. 
The other ends of the springs may engage bottom surfaces or shoulders of 
recesses 77 formed in anchor plate 72. Instead of compression spring 
mechanisms as described and shown, other spring or biasing mechanisms such 
as leaf springs, diaphragms or fluid cylinder mechanisms (not shown) may 
be employed if desired. In addition, resilient and flexible materials such 
as foam or rubber may be employed to bias the pressure member 60. 
Although the spring mechanisms bias the pressure member 60 to apply 
predetermined forces to the belt 50 which forces are distributed 
throughout a large section of the belt between the inlet and outlet 
pulleys, the springs allow the pressure member 60 to adjust or float to 
compensate for error in setting the gap G1 or variation in the thickness 
of the boards B being handled. The strength of the springs 74 are designed 
accordingly. In the preferred form of the invention, the parts are 
designed and arranged such that 0.5 p.s.i. is applied to the boards B as 
they are being fed by the belts at the gap G1. Because feeding of the 
boards B takes place while the belts are moving rectilinearly, the surface 
speed on opposite (outside) surfaces of the belts 50 and 52 remains 
substantially the same thus avoiding feeding of the boards as in 
conventional endless belt conveyors where the boards are initially engaged 
at the inlet where the belts are still moving about the lead pulleys and 
the surface speed of the outer surface of the belts is greater than the 
speed of the inner surface of the belt. The latter condition makes it 
difficult if not impossible to control or determine the speed of the 
boards B with the objective of maintaining precise register-feeding. The 
present invention uniquely avoids the problem by driving the boards with 
the belts only while they are moving rectilinearly between the lead and 
trail pulleys where the speed of the belts is precisely determined and 
controlled to provide the desired register feeding. 
Referring to FIGS. 3 and 4, the lower pressure member 62 in the specific 
form shown is fixed to a support 64 in any suitable manner such as by 
screws (not shown). A vertical support column 64 is fixed to support 64a 
and in turn is fixed to a transversely extending structural support tube 
66 which, at its opposite ends, is secured to the main frames 3 (see FIG. 
2) of the machine. Main frames 3 are vertical plates of suitable metallic 
material such as steel located on opposite sides of the feeders 28 and 30 
as shown in FIG. 2. Support 68 of the upper pressure member 60 is secured 
to vertical column 68a which, in turn, is fixed to a transversely 
extending structural support tube 70 movably mounted at its opposite ends 
to main frame plates 3. In the preferred embodiment, structural support 
tube 70 is adjustable vertically to set the gap G1 before operation. If 
there is a small error in this setting by the operator, the spring 
mechanisms 74 will compensate for the error to provide sufficient force 
and pressure distribution for feeding the boards B. 
Referring now to FIGS. 2 in the preferred embodiment, a plurality of upper 
and lower belts 50 and 52 are provided in tandem about a plurality of 
inlet and outlet pulleys. Outlet pulleys 54 and 57 are mounted on shafts 
91 and 92 suitably journalled within the main support plates 3 or in 
subassemblies mounted to the latter. Shafts 91 and 92 are driven by gears 
86 and 85 mounted to pulley shafts 91 and 92 and respectively driven by 
gears 86 and 85. The latter gears are driven by 84 and 83 respectively. 
Gear 83 also drives gear 84 while being driven by an idler gear 81 which 
also drives the input gear 82 of the planetary transmission system of the 
feeder 30 described above. Gear 81 is driven by a drive gear 80 which also 
provides the drive for the printing cylinders 22 shown in FIG. 1. 
Although ten upper belts 50 and ten lower belts 52 are employed in tandem 
in the preferred embodiment, a greater or lessor amount or even a single 
upper belt and a single lower belt may be employed in other embodiments. 
Also, in the preferred embodiment the thickness of the outer layer 50c, 
52c of belts 50, 52 is approximately 0.25 inches. Moreover, when handling 
boards B, gap G1 is approximately the same as the thickness of the board B 
and gap G2 is approximately 0.030 inches greater. 
To summarize an operation of the apparatus of the present invention, boards 
B are sequentially fed one by one by feed rolls 36, 38 under gate 34 and 
through gap G2 of conveyor 28. In the preferred embodiment, feed rolls 36 
and 38 are accelerated to drive the board from its position at rest in the 
hopper to a velocity matched to the velocity of the endless belts 50 and 
52 of feeder 28. Prior to entry into gap G1, the board reaches the matched 
velocity which is maintained constant to drive the board B until it 
reaches the downstream end of the pressure member 60 of feeder 28. At that 
time, or some time after, grate 44 will be raised to disengage feed rolls 
38 from the board. The board B will initially be engaged by belts 50 and 
52 when the board initially enters between pressure members 60 and 62. 
Belts 50 and 52 thereafter will continue engagement with the board B to 
drive it to the downstream station. During such feeding of the board, the 
pressure plate 60 will apply a force to the board controlled by the spring 
mechanisms and the placement of pressure member 60 and underlying pressure 
member 62. The force will be distributed over a large section of the upper 
belt 50 in view of the generally coextensive dimension of the pressure 
member 60 relative to the belts 50. In addition, spring mechanisms 74 will 
compensate for error in setting the gap G1 or variations in the thickness 
of board B. The above cycle of board feeding is, of course, repeated to 
continuously feed the boards B from the hopper. 
It will be seen that the present invention provides a unique method and 
apparatus which enables utilization of endless belts for feeding 
corrugated board in a box finishing machine in precise register and at the 
same time, without crushing the board. The timing belts employed by the 
present invention and the associated gear and drive mechanisms are 
obtained from commercially available materials. Moreover, the present 
invention takes advantage of the extended feeding of such feeders such as 
the EXTEND-O-FEEDtm brand feeder which has the capability of extended 
feeding of board at a constant velocity matched to the velocity of the box 
finishing machine components. 
Although a preferred method and apparatus of the present invention have 
been shown and described above, it will be understood that the invention 
should not be limited to the specific apparatus shown and described but 
rather will have applicability elsewhere and therefore the scope of the 
invention is defined in the appended claims.