Sheet feed machine

A sheet feed machine comprising guides for holding sheets in a stack at a sheet input station, a first conveyor for successively feeding sheets from the bottom of the stack at the sheet input station into a stream with adjacent sheets in an overlapped configuration, and an inverter for inverting the stream of sheets at a sheet inversion station. A stop is located at a sheet output station for stopping the stream and accumulating sheets in a stack, and a second conveyor is provided for conveying the stream of sheets from the inversion station to the sheet output station.

BACKGROUND OF THE INVENTION 
This invention relates generally to sheet feed machines, and particularly 
to the type of machines which feed sheets from the bottom of a stack 
successively into an ancillary machine such as a printer for processing. 
There are many types of machines and printers that successively process 
individual sheets of materials such as envelopes, book pages, pamphlets 
and the like. The sheets are individually fed into the printer from a 
stack as by the use of suction cups which descend atop the uppermost 
member of the stack at an input feed station and lift the uppermost member 
off and into the printer. The sheet material may be manually replaced with 
a successive stack once the stack at the printer input feed station is 
exhausted. Such manual replacement of material, however, requires that the 
printer itself be momentarily shut down and the sheet gripping mechanism 
moved aside during stack replenishing. This intermittent halting and 
restarting of printing operations has the obvious disadvantage of limiting 
the speed at which the sheet material may be printed. 
To overcome the just mentioned problem sheet feed machines have heretofore 
been devised which may be connected to the input feed station of a 
printing machine. The main function of the sheet input machine is to 
provide a place in which stacks of sheet material may be replenished 
without interrupting the operation of the printer. With these sheet feed 
machines the lowermost sheets are successively stripped from the bottom of 
the stack and fed into the printer input station. 
Unfortunately, the just described sheet feed machines have possessed 
limitations and persistent problems. Foremost among these has been the 
difficulty encountered in coordinating or timing the speed at which the 
sheet feed machine operates with that at which the printer itself 
operates. Slight mismatches in timing present errors which are cumulative 
over periods of time which can quickly lead to erroneous printing. In 
addition, these sheet feeders have lacked versatility with regard to 
material handling capability. In those case where sheets have been fed 
with adjacent sheets in a mutually overlapped condition the machines have 
tended to vary the degree of overlap beyond acceptable limits. In 
addition, even where the initial overlap and speed has been correct the 
machine has experienced difficulty in maintaining proper spacing along the 
path at which they are conveyed to the printer. The time and difficulty 
encountered in correctly attaching the feeder to the printers has also 
been substantial. 
Accordingly, it is a general object of the present invention to provide an 
improved sheet feed machine. 
More specifically, it is an object of the present invention to provide a 
sheet feed machine whose speed of operations does not have to be closely 
timed with that of an ancillary sheet processing machine which it serves. 
Another object of the invention is to provide a sheet feed machine of the 
type described with improved means for stripping sheets from the bottom of 
the stack of sheets with adjacent stripped sheets in a mutually overlapped 
configuration. 
Yet another object of the invention is to provide the sheet feed machine of 
the type described with improved means for holding a stream of sheets in 
relative position one to another as they are being fed. 
Still another object of the invention is to provide a sheet feed machine 
that may be quickly and easily attached to the sheet processing machine 
which it serves. 
SUMMARY OF THE INVENTION 
In one preferred form of the invention a sheet feed machine is provided 
which comprises means for holding sheets in a stack at a sheet input 
station, first conveyor means for successively feeding sheets from the 
bottom of a stack at the sheet input station into a stream of sheets with 
adjacent sheets positioned in an overlapped configuration, and means for 
inverting the stream of sheets at a sheet inversion station. Stop means 
are located at a sheet output station for stopping the stream and 
accumulating the sheets into a second stack. Second conveyor means are 
provided for conveying the stream of sheets from the inversion station to 
the sheet output station. 
In another form of the invention a mechanism is provided in a sheet feed 
machine for stream feeding sheets from a stack with adjacent sheets fed in 
an overlapped configuration. The mechanism comprises an upper roller 
mounted for rotation about an upper axis, a lower roller mounted for 
rotation about a lower axis located parallel with and to one side of and 
below the upper axis, and an intermediate roller mounted for rotation 
about an intermediate axis located parallel with the upper axis and offset 
above a plane passing through the upper and lower axes. A conveyor belt 
extends over the upper, intermediate and lower rollers. The mechanism also 
includes means for driving the conveyor belt and means for holding sheets 
in a stack upon the belt between the intermediate and lower rollers with a 
portion of the stack located above the belt between the intermediate and 
upper rollers. 
In yet another form of the invention a mechanism is provided in a sheet 
feed machine for holding a stream of sheets moving atop a conveyor belt in 
position relative one to the other. The mechanism comprises a beam 
pivotably mounted above the conveyor belt, a first collar mounted to the 
beam, and at least one roller rotatably suspended from the first collar 
over the belt. A second collar is mounted to the beam in spaced relation 
with the first collar and at least one other roller is suspended from the 
second collar. The mechanism also includes means for adjusting the spacing 
between the collars upon the beam to accommodate variations in feed sheet 
sizes and spacings of the sheets in the stream.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now in more detail to the drawing, there is shown a sheet feed 
machine for feeding sheets to a printer 10 such as a duplicator Model No. 
350 sold by the A. B. Dick Company. The sheet feed machine is seen to 
include a pair of angle iron guide plates 12 and a pair of upright guide 
pins 14 located upon mutually parallel inclines. The guide pins are 
mounted by wing nuts 16 to a pair of rails 18 which are in turn mounted to 
the inside of parallel side frame members 20. A main feed cylinder 22 is 
rotatably mounted between frames 20 beneath the guide plates 12. An idler 
roller 24 is rotatably mounted between the rails above and to one side of 
the main feed roller 22. An apex roller 25 is rotatably mounted to the 
side frames above a plane which passes between the axes of rollers 22 and 
24. The location of the apex roller is adjustable atop rails 18 along 
plane 27 shown in FIG. 2 for the purpose hereinafter described. 
An endless belt 26 is seen to be looped over the three rollers 22, 24 and 
25. A stack of envelopes 28 is shown set atop that portion of the belt 
located between rollers 22 and 25 with a portion overhanging that portion 
of the belt located between rollers 24 and 25. A lower edge of the stack 
is supported upon and between the guide plates 12 between the guide pins 
14. A retainer plate 30 is mounted to a bar 32 that extends between the 
two side frame members 20 with a lower lip portion resting upon a bar rest 
34 just behind the guide plates 12 and just above belt 26. The retainer 
plate is biased downwardly by a compression spring 35 held atop a retainer 
plate upper-flange by a knurled screw 36. 
The just described mechanism serves to feed envelopes successively from the 
bottom of stack 28 into a stream of envelopes with adjacent envelopes 
overlapped. This may be best visualized in FIG. 2 by following the travel 
of belt 26 as it passes from idler 24 in the direction of arrow 37 towards 
and then over the apex roller 25. Initial movement of the belt urges the 
bottom-most envelope to be stripped from the stack downwardly beneath the 
retainer plate lower lip until the trailing edge of the envelope distal 
the guides 12 has passed over the apex roller 25. As this trailing edge 
passes over the apex roller 25 the next portion of the belt 26 itself to 
pass over the apex roller 25 will follow and thus fail to engage the 
bottom-most envelope but instead engage the envelope immediately 
thereabove. At this point there will be seen that an overlap gap has been 
created which approximates the distance between the apex roller 25 and the 
edge of the stack distal the guides 12. Thus, slight relocations of the 
apex roller can effect charges in the overlap gap thereby altering the 
speed of operations. Continued movement of the belt successively causes a 
stripping of envelopes from the bottom of the stack in a mutually 
overlapped configuration. In this manner several layers of envelopes will 
simultaneously be caused to pass beneath the retainer plate 30. That the 
retainer plate 30 is spring biased in a downward direction provides an 
adjustment means by manual rotation of the knurled screw 36 in finely 
adjusting the just described operation. 
After the sheets have left the sheet input station and passed beneath the 
retainer plate lower lip 32, they are routed around under the main feed 
cylinder 22 at the sheet inversion station. This is accomplished by the 
simultaneous actions of conveyor belt 26 as it moves about the main feed 
cylinder and another conveyor belt 40 which is routed over a drive roller 
42, an idler 44 and a tension adjust roller 45. As a portion of the main 
feed cylinder 22 lies in a plane passing tangentially over rollers 42 and 
44, belt 40 is seen to curve inwardly as it passes over the main feed 
cylinder. The velocity of the drive roller 42 is set to cause the conveyor 
belt 40 to move at the same speed as the conveyor belt 26 does over the 
main feed cylinder 22. It thus is seen that with a stream of envelopes 
carried atop belt 26 they will be sandwiched between belts 26 and 40 as 
they are conveyed down and around the main feed cylinder 22. In this 
manner it is seen that the stream of envelopes is inverted. 
After the stream of sheets has been inverted it is guided onto a horizontal 
feeder tray 50 over which another endless conveyor belt 52 is driven as 
shown in FIG. 3. This conveyor belt 52 is routed over a drive shaft 54, a 
front idler 55 and a pair of tension rollers 56 and 57. A U-shaped leg 58 
is pivotably mounted to parallel frame support 60 to each side of the 
feeder tray which leg is sized to be placed atop the printer elevator. An 
electric motor 66 is mounted between another U-shaped leg 64 having its 
output drive shaft coupled with a drive belt 68 that drives shaft 54. 
Unshown endless chains in turn couple the main drive shaft with the other 
drive cylinder 22 and roller 42 for driving belts 26 and 40 while the main 
drive shaft itself drives the conveyor belt 52. The U-shaped leg 64 is 
mounted atop a stanchion 70 which is telescopically received within 
another stanchion 72 that extends uprightly from a platform 74 supported 
upon a floor by a set of casters 75. This telescoping arrangement of the 
stanchion enables the height of the sheet feed machine to be adjusted. 
This height adjustable feature, coupled with the pivotably U-shaped front 
leg 58 and strap 62, enable the sheet feed machine to be readily connected 
with numerous sheet processing machines such as printers in a minimum of 
time and with a minimum of effort and training. 
The sheet feed machine also includes a mechanism for holding the stream of 
sheets down upon the top of the conveyor belt 52 with adjacent sheets in 
the stream maintained in mutual relative position. This hold-down 
mechanism includes a beam 71 pivotably mounted by pivot pin 76 above the 
conveyor belt 52. A collar 73 is slideably mounted by set screw 79 to the 
beam which collar supports a trolley arm 80 to which a trolley 82 is 
pivoted. The trolley in turn supports a pair of mutually spaced rollers 
84. Another collar 85 is slideably mounted by a screw 86 to the beam. A 
pair of legs 78 is pivotably mounted to this collar 85 with each leg 
supporting a roller 90. A tension spring 92 couples the two legs 78 
together. Finally, a rear wheel 94 is pivotably mounted to the beam 
closely adjacent to the pivot pin 76. With this hold-down arrangement the 
members in a stream of sheets passing atop belt 52 and tray 50 are held in 
firm engagement atop the belt 52 with relative movement between the 
members in the stream inhibited. It will also be seen that the collars 73 
and 85 enable the spacing of the various rollers of the hold-down 
mechanism to be altered to accommodate variations in sheet sizes and 
overlap spacings. The rear most roller 94 is purely optional, being 
preferred only for very small envelopes. 
Finally, the sheet feed machine is seen to include a microswitch 96 to 
which an actuating arm 97 is mounted. The microswitch 96 serves to 
terminate, through unshown electrical circuitry, the operation of the 
electric motor 66 in driving the various conveyor belts 26, 40 and 52 when 
a stack 98 of sheets has been accumulated beneath a suction pickup arm 99 
of the printer or other sheet processing machine. Once this actuating arm 
97 has fallen from the removal of sheets from the stack faster than they 
are being resupplied, motor 66 is reactivated to feed additional sheets 
into the pickup station. The sheets are accumulated here by the provisions 
of stop 100. 
It should be understood that the just described embodiments merely 
illustrates principles of the invention in preferred forms. Many 
modifications, additions and deletions may, of course, be made thereto 
without departure from the spirit and scope of the invention as set forth 
in the following claims.