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Description  |
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This invention relates to signature gathering and in particular to a
signature feeding machine for extracting a signature from a hopper and
dropping it on a conveyor. The disclosure specifically concerns a machine
for feeding a saddle gatherer or conveyor but some principles of the
invention are equally applicable to flat gathering.
A machine of the foregoing kind (for saddle gathering) typically may
include a suction gripper, mechanical grippers on an extracting cylinder,
and mechanical grippers both on a lap cylinder and an opening cylinder,
which cooperate first to present the signature to the extracting cylinder,
to fully extract a signature from the hopper and thereafter to open the
pages so the signature may be dropped in straddle relation on a saddle
conveyor, along with other signatures handled in a similar fashion to
complete a book, usually a stitched back book.
A book is simply a collection of signatures, regardless of the number of
signatures and regardless of the manner in which the book is bound. A
signature, in the simplest form, is a folded sheet. If it is folded
off-center it has a short leg and a longer leg, the latter presenting what
is known as a lap margin.
Our company on several occasions has addressed itself to improving
productivity in the production of books using grippers on an extracting
cylinder. In U.S. Pat. No. 3,565,422 for example, there was an effort to
enlarge productivity by increasing the number of grippers on the
extracting cylinder from two to three (an increase of fifty percent) with
the intention of correspondingly increasing the speed of the lap and
opening cylinders, in order to keep pace.
In principle the idea of increasing from two to three the number of
signatures handled during one turn of the extracting cylinder is correct
but when the speed of the lap and opening cylinders is increased all sorts
of difficulties are encountered due to the increased velocity. It is not
the increased velocity of the parts of the machine which present
difficulty, rather the increased velocity of the paper, paper dynamics
indeed. Thus, nearly all the equations involving resistances and
impedances encountered by the paper signatures involve the exponential
factor of v.sup.2 (v=velocity). The resistances and impedances involve
such things as the kinetic energy of the paper in motion, the air foil
character of the signature in motion, centrifugal force, uniform
acceleration, air resistance and so on. This explains why we found
disadvantages and not advantages when increasing the velocity of the lap
and opening cylinders to keep pace with the increased amount of paper when
increasing the number of grippers on the extracting cylinder.
It was a realization of the adverse effect of the v.sup.2 factor which
prompted the thought that the way to handle signatures delivered by a
three gripper extracting cylinder was to slow the lap and opening
cylinders, not speed them up, and to handle the increased delivery from
the extracting cylinder (three sheets instead of two per cycle) by a
second gripper on each of the lap and opening cylinders.
Accordingly, an object of the present invention is to be able to accomodate
an increased rate of signature extraction without having to increase the
speed of the lap and opening cylinders and more specifically it is an
object of the present invention to accomplish this by actually slowing the
speed of the lap and opening cylinders by adding an extra gripper to each
one, allowing the speed of the lap and opening cylinders to be decreased
with the result that the delivery rate is increased while actually slowing
the speed.
Experience has established that the superior way to extract a signature
from a supply hopper, incidental to finally delivering it to a saddle
conveyor, is by way of oscillating suction grippers which are effective to
clamp a signature by vacuum and pull it out of the hopper in position to
be grabbed by the gripper on the extracting cylinder. In actual practice
there may be as many as thirty or forty signature feeders in a row, each
feeding the saddle or gathering chain. As can be imagined it is sometimes
necessary to stop the machine in order to clear a jam in one of the
signature feeders and this indeed may entail a prolonged effort to
identify the source of the problem during machine shut-down. In
accomplishing the repair it is sometimes necessary to "jog" the pocket
feeder in order to identify the source of the problem causing the paper
jam. It is therefore customary for the manufacturer of the signature
feeder to provide for two different controls, namely, a continuous or
un-interrupted mode and a discontinuous or jog mode. The signature feeder
of the present invention, as may be inferred from the foregoing, is
characterized by an extracting cylinder having three grippers spaced
equidistantly about the circumference. There is a very brief interval
between the time a signature is pulled from the hopper, by means of the
suction extractor, and the time when the backbone of that signature is
grabbed by a gripper on the extracting cylinder. In accomplishing this
movement, that is, the movement of the signature from the supply hopper
into position to be grabbed by the gripper, vacuum must first be applied,
held and then disapplied so that the vacuum grip is discontinued at the
moment the mechanical gripper is actuated.
Provision must therefore be made to disapply vacuum before the mechanical
gripper is actuated and to re-apply the vacuum neither too late nor too
soon with respect to the next signature to be extracted from the supply
hopper. In the ordinary machine, where there are one or two grippers on
the extracting cylinder with proportionally reduced speed, the movement of
the suction gripper, back and forth, is considerably less critical in
timing than where there are three grippers and our realization of this
fact lead to the discovery of the problem and its answer. Thus, with the
machine in a jog mode nearly all the inertia of an idle machine prevails,
but when the suction fingers are oscillating with great speed in the run
mode to feed the mechanical grippers (indeed fifty percent faster than
heretofore with a two gripper cylinder) the timing of application and
disapplication of the vacuum is quite critical, which explains why we
found signatures being mishandled in the run mode but not in the jog mode.
We found the other way around to be also true: timing for the run mode
distorted the jog mode, which is to say that when the machine is placed in
the jog mode, which is necessary for trouble shooting, the vacuum timing
which prevailed in the run mode was obscuring identification of the real
problem.
Accordingly another object of the present invention is to enable a machine
of the foregoing kind, that is, a signature feeding machine, to be timed
differently, in two different modes of operation, from the standpoint of
application and disapplication of vacuum (negative pressure) prevailing in
the suction means used to extract the signatures from the hopper and
present each signature properly to the mechanical gripper supported on the
rotating extracting cylinder. More specifically it is an object of the
present invention to be able to select between two rotary valves which
time the application (and disapplication) of the vacuum differently for
the respective run and jog modes.
The term "jog" is employed in the express dictionary sense, meaning to
cause the machine to operate for an instant as by a button which permits
momentary operation of the motor. In comparison, the machine is otherwise
in its "continuous run" mode, that is, no discontinuity in repeated
machine cycles or portions thereof.
IN THE DRAWING
FIG. 1 is a side elevation of the machine with parts in section;
FIG. 2 is a detail view of vacuum valving parts;
FIG. 3 is a sub-assembly view of parts shown in FIG. 2;
FIG. 4 is a view on the line 4--4 of FIG. 3 with some hoses connected in
place;
FIG. 5 is a view on the line 5--5 of FIG. 3;
FIGS. 6 and 7 are taken on the line 6--6 of FIG. 3;
FIG. 8 is a view taken on the line 8--8 of FIG. 1.
The signature feeding machine 10, FIG. 1, comprises an extracting cylinder
12 positioned above a lap cylinder 14 and an opening cylinder 16.
The signatures are stacked in a hopper 18 with their backbones down and
with the short sheet front-most so that for the leading signature, next to
be extracted, its short sheet reposes against the front plate 20 of the
hopper while its backbone (fold) is at the throat (opening) 22 at the
bottom of the hopper, in position to be grabbed by one of several suction
grippers 24.
Each suction gripper is carried at the lower end of a hollow stem 26
depending from a horizontal, hollow support rod 27 which also serves as a
suction manifold for communicating vacuum to the suction grippers.
The support rod 27 is carried by an oscillating bell-crank 28 pivoting at
29. The bell-crank is oscillated by a three lobed cam 30 engageable with a
cam follower 31 secured to the bell-crank 28 so that the suction grippers
are caused to swing in and out relative to the throat of the hopper. When
the suction gripper swings in, it contacts the forwardmost signature in
the hopper and grips it by suction; during the reverse or outward stroke
the suction gripper presents the backbone of the withdrawn signature to
the periphery of the extracting cylinder.
Cam 30 rotates with the extracting cylinder and actuates the suction
grippers three times for each turn of the extracting cylinder,
transferring three signatures for each turn of the extracting cylinder.
The extracting cylinder rotates counterclockwise as viewed in FIG. 1. It
carries three gripper fingers 32-1, 32-2 and 32-3 equidistantly spaced
about the circumference thereof, each secured to a rod 36 (three rods in
all) in turn supported by the cylinder 12 for revolution therewith. The
term "extracting cylinder" is a term of art; it actually comprises two
spaced discs 12-1 and 12-2, FIG. 8, each equipped with the three grippers,
and a third disc 12-3 carrying the segment gear rockers described below.
The rods 36 are rotatable and each has a pinion 38 at one end, engaged with
a segment gear 40. Each segment gear is part of a rocker 42, pivotally
supported at 44 on the extracting cylinder, and biased by a spring 45.
Each segment gear rocker has a cam follower 46 in position to ride on a
stationary timing control cam 48 coaxial with the extracting cylinder. Cam
48 has a single lobe and a single dwell so that cam 48 and the cooperating
springs 45 are effective to open and close the respective grippers 32-1,
32-2 and 32-3. The spring tends to close the gripper; the high part 48-H
of cam 48 rocks the gear segment to open the gripper.
Finger 32-1 is shown in FIG. 1 in its closed position, effective to clamp
the backbone of an extracted signature against a cooperating anvil 32-A,
transporting the signature counterclockwise in the direction of a register
gauge 50, with the backbone in leading position. This closing of the
gripper, to extract, is a critical feature of timing and is unchangeable
regardless of signature length.
Another critical feature of timing is that the grippers on the extracting
cylinder must be open when the backbone of the signature reaches the
register gauge which is pre-positioned depending on the length of the
signature. The register gauge will be so positioned that the signature
released thereto will have its lap drooping in contact with the periphery
of the lap cylinder 14.
The cam 48 will be positioned initially at the time of installation so the
grippers will close properly on the backbone presented by the suction
disc. Likewise, the register gauge will be properly adjusted. Then, an
adjustable cam patch 52, FIG. 8, keyed to cam 48 is turned to lengthen or
shorten the effective cam dwell surface (depending on signature length) to
allow the grippers to be opened by the cam lobe 48-H just when the
signature backbone is at the register gauge; the grippers remain open with
the cam follower 46 riding on the cam lobe until they are once more back
on the hopper side when the cam follower rides off the cam lobe, allowing
the spring to close the gripper.
When the signature is released to the register gauge, its extended, free
lap margin is presented to the lap cylinder 14 and more specifically
dangles in the six o'clock position to be grabbed by either one of two
gripper fingers 62-1 and 62-2 carried by the lap cylinder 14 in
180.degree. displaced positions. The lap cylinder is equipped with
actuating means to open and close the lap gripper fingers, operating in a
manner identical to the extracting cylinder grippers as can be seen from
the timing control cam 64, follower 65, spring 66, pinion 67, segment gear
68, and segment gear rocker 69 for each set of lap grippers. The lap
gripper fingers are carried on a shaft 62S having the gear 67 at one end
as shown in FIG. 8. Thus, a lap cylinder gripper is effective in timed
relation at its twelve o'clock position to clamp the lap of the signature,
positioned in the register gauge, against an anvil as 62A, withdrawing the
signature from the register gauge leftward as viewed in FIG. 1, beneath
the lower surface of a guide 71. The upper surface of guide 64 serves as a
guide for the signature during its transit from the hopper to the register
gauge; a second guide 72 near the register gauge serves the same purpose,
guiding the signature into and out of the register gauge.
The opposed opening cylinder is also provided with a pair of 180.degree.
displaced, finger-like grippers 70-1 and 70-2, operating and timed in the
manner of those on the lap cylinder as can be readily seen. In this
connection it will be recalled the effective surface on cam 48 can be
varied by the cam patch 52; similar cam timing patches are afforded for
the lap and opening grippers.
The lap cylinder rotates counterclockwise, the opening cylinder rotates
clockwise. As already noted, one set of the grippers on the lap cylinder
(say 62-1) is effective to clamp the lap of the signature, moving the
signature toward the bight between cylinders 14 and 16, and as the bight
is attained the opposed fingers on the opening cylinder (say 70-1) are
interdicted between the signature sheets, closing at the three o'clock
position; thereafter fingers 62-1 and 70-1 cooperate to spread the
signature sheets out more and more until the divergence is adequate to
assure the signature will straddle the saddle 74. Preferably the lap and
opening grippers are opened at their six o'clock position.
The cams on the lap and opening cylinders, which control their grippers,
are also adjusted at the time of installation so the action of those
grippers will be timed to the gripper on the extracting cylinder.
During one 360.degree. turn of the extracting cylinder, three signatures
are withdrawn one by one in sequence from the hopper and released to the
register gauge. When the lap gripper picks up a signature in the signature
gauge, the next or following signature is already on its way toward the
register gauge.
As shown in FIG. 8, the extracting cylinder is supported on a drive shaft
75 having a sprocket 76 driven by a chain (not shown). The lap cylinder is
supported on a drive shaft 78 and the opening cylinder is supported on a
drive shaft 79, each having a sprocket as 81 driven by the same chain.
It may seem parts are merely being multiplied. That is by no means the case
as will now be explained. In the known machine there were two grippers on
the extracting cylinder separated by approximately 17.3 inches for a total
circumference of 34.6 inches. There was only one gripper on each of the
lap and opening cylinders, each of these cylinders having a circumference
of about 17.3 inches. In a machine of this character, the base or index
can be taken as the rate of the stitcher head where the books are
stitched. Assuming a stitcher head rate of 225 books per minute, the rate
of paper dropped on the saddle (and into the register gauge as well) would
be 17.3 .times. 225 = 3890 linear inches per minute, which was the
approximate maximum rate of the known machine because of the v.sup.2
factor involving paper dynamics.
In the present machine, the three extracting grippers are spaced by 13.1
inches (39.3 inches circumference) and those on the lap and opening
cylinders are separated by 11.9 inches (23.8 inches circumference).
Assuming a v.sup.2 value of one (velocity=1) for paper dynamics in the
known machine, the following chart shows how that value is reduced
considerably under the present invention:
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v.sub.2 (at the
Machine Cycles/min. register gague)
v.sup.2 (at the saddle)
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Known 225 1 1
Present 225 0.6 0.47
275 0.86 0.70
300 1.02 0.84
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The v.sup.2 factor features constantly: accelerating paper from the hopper,
throwing it into the register gauge, re-accelerating it out of the
register gauge, opening the pages and finally allowing it to drop on the
gathering chain. In effect the linear velocity of paper between the supply
hopper and the gathering chain is slowed but the number of signatures
delivered per unit of time is increased.
It can be recognized from FIG. 1 that the grippers are closely spaced,
leaving both little space and little time for reciprocating the sucker
head 24, cycling the suction on and off, and closing of the gripper, which
are events of critical importance at the throat of the hopper. If there is
not precise coordination the signature will be torn or missed during the
continuous run mode. Thus, the suction must be fully released when the
grippers as 32-1 clamp the backbone of the signature to the anvil 32-A.
To enable the two modes of operation to be handled (run mode; jog mode) two
separate valving means are employed for cycling the vacuum, preferably
rotary valves. Thus, referring to FIGS. 2 through 7, vacuum is effective
at all times in a hose 80 and is continuously communicated to two
receiving ports RL and JL (R for "run"; J for "jog") provided in a
stationary porting disc 82, which is co-axial with drive shaft 75, located
at the side of the machine near the drive sprocket 76. A second disc 84 is
keyed to cam 30 for rotation therewith synchronously with the extracting
cylinder and fits snugly against disc 82 in sealed relation.
Disc 84 is a valving disc, formed in the face next to disc 82 with a first
series of equidistantly spaced segmental valve slots R-1, R-2 and R-3 (R
for "run") arranged on a radial outward circle, and a second series of
equidistantly spaced segmental valve slots J-1, J-2 and J-3 (J for "jog")
arranged in a radial inward circle. There are three valving slots (segment
angle alpha) accordingly as there are three sets of grippers on the
extracting cylinder.
The stationary porting disc 82 is provided with a pair of vacuum transfer
ports RS and JS. Port JS is communicated to a hose 88 in turn connected to
a solenoid-operated valve 90. Port RS is connected by a coupling 92 to
valve 90. Valve 90, in turn is connected by a hose 94 to the manifold pipe
27 which services the sucker heads.
The solenoid valve is a selector enabling vacuum to be handled selectively
for the two modes: it is open during the run mode to discommunicate port
JS with the vacuum and closed during the jog mode to discommunicate port
RS with the vacuum. Thus, in each mode vacuum will be effective at either
port RS or port JS but not the other port.
There is one bleed port (bleed to atmosphere) RB and a second bleed port JB
in disc 82 for releasing the vacuum prevailing in the sucker head manifold
27.
The ports are so spaced and the valve slots of such length that a valve
slot can span two adjacent ports but not three, thereby to communicate a
vacuum transfer port to either the vacuum receiving port or the
bleed-to-atmosphere port.
Referring to FIGS. 6 and 7 (both taken in the direction of the arrow 6--6,
FIG. 3, so the valving slots may be viewed as juxtaposed on the ports of
disc 82 in the operative state) it will be noted the leading edge of valve
slot R-1 has just touched port RS to establish communication with port RL
where vacuum prevails, meaning vacuum is started to the sucker heads,
assuming the run mode prevails; in FIG. 7, the same valve slot has
afterwards just attained port RB to communicate the sucker heads to
atmospheric pressure in the run mode.
The condition is slightly different for the jog mode valve slots; they
"lag" the run mode by a predetermined angle, say 5.degree. to 10.degree..
Thus, in FIG. 6, the leading edge of slot J-1 would be communicating with
port JL, not yet having attained port JS at a time when vacuum would
already have prevailed at the sucker heads in the run mode. Similarly,
FIG. 7, the leading edge of slot J-1 would be displaced from the
bleed-to-atmosphere port JB at the time when atmospheric pressure would
already have started to prevail at the sucker heads in the run mode.
The net effect is vacuum is discontinued at the sucker heads in their
movement toward the extracting cylinder, to release the signature, sooner
than in the jog mode. Similarly, during the return stroke of the sucker
stems toward the pile of signatures in the hopper, vacuum is sooner
applied than in the jog mode.
We prefer to employ a dual, selectable rotary valve for varying the time of
applying and disapplying negative pressure in accordance with two basic
modes of machine operation because we can thereby synchronously harness
the rotary input to the extracting cylinder. Nonetheless, a linear slide
valve presenting equivalent porting could conceivably be used. Because a
rotary valve can thus be easily made self-synchronizing it would be
possible to dispense with one series of valve slots in disc 84 while
making provision to automatically turn disc 84 selectively in one
direction or the other by an angle proportional to machine speed, as by a
governor responsive to speed of the extracting cylinder, in which event
there may be more than two settings but nonetheless inclusive of a jog
mode as the slowest.
The valving principle could also be incorporated in a flat gathering
machine where again signatures may be pulled one by one from a hopper by
an oscillating vacuum disc which presents the signature in sequence to
spaced gripper means on a rotary extracting cylinder which in turn release
the signatures for gravity drop on to a so-called flat or side gathering
conveyor, without intervention of a lap and opening cylinder which
characterize a saddle conveyor for signatures.
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