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Description  |
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CROSS-REFERENCE TO RELATED APPLICATIONS
The present application is related to U.S. patent application Ser. No.
87,839, filed Oct. 24, 1979, brake for sheet stacks on a folding table,
and assigned to a common assignee.
FIELD OF THE INVENTION
The present invention is directed to a method and to apparatus to execute
this method to produce folded sheet stacks, a group of paper ribbons
comprising a plurality of paper ribbons being cut by an appropriate means
into a series of sheet stacks, this series of sheet stacks being
subsequently split up into at least two streams of sheet stacks and
folded.
DESCRIPTION OF THE PRIOR ART
Folders which cut and fold paper webs brought together from several
printing units, and which deliver the folded sheet stacks, for example in
the form of newspapers, in a shingled array, are known in different
designs. In these devices, two ore more cylinders perform the cutting, the
collecting of individual signatures of sheets, if need be, and the cross
folding perpendicularly to the machine direction. Cross folding is done at
full paper speed either between two cylinders by means of a folding blade
and a folding jaw, or by means of a rotating folding blade, which
protrudes from the periphery of a rotating cylinder, the tip of the
folding blade covering a stationary hypocycloid and pushing the newspaper
signature to be cross-folded into two stationary counter-rotating folding
rollers. An advantage of the gear folder system is its sturdy design, so
that even thick signatures, for example of 144 pages, may still be
processed. It is, however, a disadvantage, that folding is done at full
paper speed and with an immediate reverse motion of the preceding
pinned-up edge of the signature. This imposes speed limits within the
system, since otherwise the signatures may be damaged by the so-called
"whip effect".
It has been attempted (see German Pat. Nos. 17 61 074 and 18 01 419) to
divide the stream of sheet stacks prior to cross-folding them, to
decelerate the speed of the sheet stacks by approximately 30%, and to
execute the cross fold itself at a relatively slower peripheral speed.
Apart from the great technical expenditure required, even in this case it
is impossible to remedy one principal disadvantage of the gear folder;
that the tip of the folding blade viewed against a resting system,
executes only a stationary hypocycloid, usually a three-point star of a
straight line. In the rotating cylinder, however, the tip of the folding
blade executes a circle. It pricks from below into the sheet stack
approximately in the middle of the distance between the pins and the cross
fold to be made, and moves at considerable speed and with a scratching
effect backward relatively to the paper. Simultaneously, the blade lifts
the sheet stack off the quickly rotating cylinder periphery, until the
folding rollers engage and execute the cross fold. Thereby, the
above-described "whip effect" appears. Furthermore, the immediate reverse
motion of the advancing sheet stack edge requires that the pins be
withdrawn in time, so that the sheet stack "drifts" more or less free for
a short way prior to being cross-folded, that is before the folding
rollers "grip". This results in the well-known and disadvantageous
dependency on speed, which means that the cross fold given to the sheet
stack which is to be folded to a newspaper, will be executed in the same
position only if the machine speed remains constant, and must be
readjusted by hand or by means of complicated automatic devices to the
middle of the sheet stack if the speed is changed.
The jaw folder principle avoids such disadvantages, since there is not
considerable relative motion between the sheet stack to be folded and the
folding blade. The sheet stack does not "drift" at the moment of folding,
since the pins continue holding the stack and open slowly after the
folding jaw has been closed. Thus the cross fold is produced at any speed
at the same point of the sheet stack. The "whip effect" on the advancing
edge of the sheet stack is also less intense, since the change of the
direction of motion, although not being neutralized, is not done abruptly,
but gradually. It is an advantage that the jaw folding system is thus
capable of producing a more precise cross fold at higher speeds without
damaging the sheet stack. It is, however, a disadvantage, that there are
limitations to the capability of the folding blade-folding jaw system, so
that newspapers usually to only 64 pages, or up to a maximum of 80 pages
can be cross-folded.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method to produce
folded sheet stacks, for example newspapers, and to provide apparatus to
execute this procedure, thus enabling the cut-off of very thick sheet
stacks comprising 144 or more pages from a plurality of paper webs brought
together, to cross fold said sheet stacks exactly, independently of the
machine speed, and to deliver said sheet stacks, at high speeds. If
required, the production of straight run and collected production is
enabled.
According to the invention there is provided a procedure to produce folded
sheet stacks in a folder of a web-fed rotary printing press, a group of
paper ribbons comprising a plurality of paper ribbons being cut by an
appropriate means into a series of sheet stacks, and being subsequently
split up into at least two streams of sheet stacks. Furthermore, there is
provided, according to the invention, a mechanism to execute this
procedure, comprising a plurality of formers and a device for bringing the
plurality of paper ribbons together into at least one group of paper
ribbons, comprising furthermore at least one cross cutting cylinder group
to cut the group of paper ribbons into a series of sheet stacks, and one
conveyor cylinder equipped with controlled sheet stack conveyor means, for
example with pins, which cooperate with at least two take-over cylinders
equipped with controlled sheet conveyor means.
The following particular advantages result from the present invention.
Since, according to the invention, rotating folding blades and stationary,
counter-rotating folding rollers of sturdy design cooperate with each
other, cross-folding of very thick sheet stacks into newspapers is enabled
as in the well known gear folder. Because the folding blade enters a
stationary sheet stack, there is practically no relative motion between
the sheet stack and the folding blade as in folding by means of folding
jaws, so that, as an advantage, in spite of the gear folding principle
used, the cross fold no longer depends upon speed. Cross-folding even the
thickest sheet stacks is done at all speeds at the same point of the sheet
stack. The folder speed may be considerably higher for two reasons: due to
distributing the stream of sheet stacks onto at least two folding tables,
the sequence of the sheet stacks is at least divided into halves.
Therefore the rotating folding blade performs only half or less the number
of strokes, so that the folding-off speed and thus the "whip effect" are
divided in half or even to less that that. Additionally, the speed of the
advancing edge of the sheet stack is not abruptly changed from the
positive to the negative direction of motion, but begins from zero speed
so that the "whip effect" is once more diminished to one half.
Furthermore, since the position of the folding rollers and the folding
blade is at right angles to the direction of motion, the sheet stacks are
folded off in the direction of paper motion. Thus, the following sheet
stack does not have to wait, as is the case in longitudinal folding
mechanisms, for the so-called third fold; i.e. the second longitudinal
fold until the entire sheet stack has completely passed through the
folding rollers, but may immediately follow the rear edge of the preceding
sheet stack. This enables the use of an essential deceleration of the
sheet stack before the stack arrives at the stops on the folding table,
whereby the kinetic energy of the sheet stacks is once more reduced, when
they are braked.
As a further advantage, the thick sheet stacks which have been cross-folded
to newspapers, are distributed by the high speed folder in accordance with
the present invention onto two or more deliveries, from which result good
starting conditions for handling the newspapers in the dispatch room. The
quality of the cross fold in the newspaper products is better in spite of
high speeds and great numbers of pages, since there is no relative motion
nor any scraping caused by the folding blade on the fresh print on the
inner newspaper page, and since there is essentially less tearing of the
sheets caused by the "whip effect". Furthermore, the novel stop bar
systems on the folding tables, which act as impulse absorbers, enable
exact stopping of the heavy sheet stacks prior to the cross fold, which is
important for high folding precision.
BRIEF DESCRIPTION OF THE DRAWINGS
While the novel features of the folding procedure and the folding mechanism
in accordance with the present invention are set forth with particularity
in the appended claims, a full and complete understanding of the invention
may be had by referring to the detailed description of preferred
embodiments as set forth hereinafter and as shown in the accompanying
drawings in which:
FIG. 1 is a schematic cross-sectional view of a folder for the production
of newspapers comprising 160 pages in straight run production onto either
delivery, with horizontally disposed folding tables in accordance with the
present invention;
FIG. 2 is a schematic cross-sectional view of a folder for the production
of newspapers in collect run or straight run production with inclined
folding tables in accordance with the present invention;
FIG. 3 is a schematic cross-sectional view of a folder for the production
of newspapers with 160 pages in straight run production onto either
delivery, as shown in FIG. 1, with inclined folding tables in accordance
with the present invention;
FIG. 4 is a plan view, partly in section, of a sheet stack brake drum with
hinged, pulled-out stop rod and drive for the drum in accordance with the
present invention; and
FIG. 5 is a sectional schematic view of the sheet stack brake drum taken
along line IV--IV of FIG. 4 without side frame in accordance with the
present invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
It is known in the art to convey sheet stacks onto a folder, to brake them,
and to fold them by means of folding blades and folding rollers. In that
case, however, the question is mechanisms which produce a so-called third
fold, or second longitudinal fold. The sections which arrive on the
folding table have been cross folded before in a jaw folding or gear
folding system, including all the restrictions for the cross fold as
mentioned above. The folding mechanism in accordance with the present
invention uses, however, folding tables the folding rollers and folding
blades of which are not disposed in the paper direction, but are turned
90.degree., and the cross fold which until now had its problems, is no
longer produced in the moving newspaper, by means of folding cylinders but
on resting signatures on folding tables in accordance with the present
invention.
As may be seen in FIG. 1, for the production of newspapers of 160 pages in
straight run production, ten paper webs come from printing units of eight
plates' width (not shown in the drawing) and are conveyed over eight
formers 1-8 in a balloon disposition. Each four longitudinally folded
paper ribbons 9, 10, 13, 14 and 11, 12, 15, 16 are joined below the
formers 5, 6, 7, 8 to form paper ribbon groups 19, 20 each, the thickness
of each of the paper ribbon groups being that of 40 paper thicknesses.
These groups of paper ribbons 19, 20 are conveyed in a straight line to
one driven cross-cutting cylinder group 21 or 22 which are equipped with
staggered cutting knives. When the groups of paper ribbons 19, 20 have
been cut to sheet stacks 23, tape guides 24 running in gaps between the
cutting knives of the cross-cutting cylinder group 22 convey the sheet
stacks 23 to a four-field pin collecting cylinder 27, which joins the
sheet stacks 23 by pinning them up. The sheet stacks 23 are then
alternately conveyed to take-over conveying cylinders 28 and 29. Take-over
cylinders 28, 29 are equipped with pluralities of sets of pins 30 or 31,
respectively, which are capable of being controlled, and which convey
sheet stacks 23, which have not yet been cross-folded, to a folding table
portion 34 or 35, which in this case are horizontally disposed of the
cross folding device 79 or 80, respectively, the sheet stacks 23 stopping
against stop rods 138-142 shown, as an example, in FIG. 1 and described in
detail hereinafter. By means of rotating folding blades 38, 39, the sheet
stacks 23 which are at rest, are pushed into driven folding roller pairs
40 or 41, so that they are cross folded from their resting position. Each
cross folding system 34, 38, 40, or 35, 39, 41 respectively, runs at half
the number of strokes in relation to the number of cross folded sheet
stacks 23. Each sheet stack 23 may, after having left the pin cylinder 27
and prior to being pushed at the stop rods 138-142, be slowed down in its
running speed in such a way, that the front edge of the next following
sheet stack 23 on that folding table does not quite reach the rear edge of
the preceding sheet stack 23. One delivery fan each 42, 43 with adjoining
delivery tapes 44, 45 is disposed below the pairs of folding rollers 40
and 41. It is furthermore possible to install pairs of folding rollers
(not shown in the drawing) below the pairs of folding rollers 40 and 41 in
order to slow down the speed at which the signatures 46, 47 are placed in
the delivery fans 42 and 43.
Modifications to the folder described above and shown in FIG. 1 are
practicable, for example; all the longitudinally folded paper ribbons 9-16
may be joined below the formers 5-8 to two groups of paper ribbons and
cross-cut in this way, instead of one group of paper ribbons, since a
plurality of cross cutting cylinder groups 21, 22 are provided. Instead of
the controlled pins 48, 30, 31 on the cylinders 27, 28, 29, it is also
possible to provide grippers, if the cylinder peripheries are accordingly
somewhat enlarged. It is an advantage that in this case the problems with
respect to pinning-up are avoided as well as the production of paper dust
caused by that pinning-up.
As may be seen in FIG. 2, ten paper webs which run over three formers (not
shown in the drawing) are then joined to form a group of paper ribbons 49
and are seized by controlled pins provided on a five-field cutting groove
and collecting cylinder 51. Cross-cutting the paper ribbon group 49 into
sheet stacks 56 is done by means of a cutting cylinder 53 equipped with
two cutting knives 54, 55 which operate centrically or, in collect run
production; eccentrically. In straight run production, the pins 50 deliver
the sheet stacks 56 alternately to controllable pins 61 or 62, which are
provided on take-over cylinders 57 or 58. Tape guides 59 or 60 convey the
sheet stacks 56, which have not yet been folded, alternately onto folding
tables 63 or 64 which are both disposed at an angle .alpha. to the
horizontal line. These sheet stacks 56 are conveyed to stop rods 138-142
whose operation will be described in detail with respect to FIG. 4 and
FIG. 5. Rotating folding blades 65, 66 of the cross folding devices 79 and
80 push the sheet stacks 56 for cross folding from their resting position
on the folding tables 63 or 64 into pairs of folding rollers 67, 68, which
are disposed crosswise to the direction of motion of the sheet stacks 56,
and then to the delivery fans 69 and 70. The conveyance of the cross
folded sheet stacks 56 from the folding roller pairs 67 or 68 to the
delivery fans 69 or 70 is done by means of driven tape guides 73, 74. The
alternating opening of the pins 50 provided on the cutting groove and
collecting cylinder 51, or of the pins 61, 62 provided on the take-over
cylinders 57, 58 may, for example, be done by means of a control mechanism
as described in German Pat. No. 18 01 419, so that the straight run
production is distributed to both delivery fans 69, 70 or to the delivery
tapes 71, 72. In collect run, every first sheet signature runs one time
around the cutting groove and collecting cylinder 51 and is then joined
with a second sheet signature, before the pins 50 deliver the now
collected sheet stack 56 either onto the take-over cylinder 57 or
alternatively onto the take-over cylinder 58. It is also possible to split
the sheet stacks by collecting them alternately onto both take-over
cylinders 57 and 58. The rotating folding blades 65, 66 run each at half
the stroke number of the the total production of sheet stacks 56. In the
case of simultaneous collecting and splitting-up, a quarter of the stroke
number is sufficient.
The folder shown in FIG. 3 is identical with the folder described with
respect to FIG. 1, as regards its function. Therefore, the description
with respect to FIG. 1 is valid for this folder also. Identical parts are
marked with identical numerals. There is, however, a difference between
the folders of FIG. 1 and FIG. 3, namely in that the folding tables 34 and
35 of FIG. 3 are not disposed horizontally, but are at an angle .beta. to
the horizontal line. It is an advantage that the surfaces of the folding
tables 75 and 76 of the cross-folding mechanism 79, 80 lie on a tangent 77
or 78 on the periphery of the take-over cylinders 28, 29.
Conveyance of the cross folded sheet stacks 23 from the folding roller
pairs 40 or 41 to the delivery fans 42 or 43 is done by means of tape
guides 73 or 74. These tape guides 73, 74 may run at a lower tape speed to
enable slowing the signatures down. Furthermore, the gap in the folding
table over the folding rollers may temporarily be bridged by appropriate
means (not shown in the drawing), so as to guarantee a trouble-free
introduction of the sheet stacks above this gap.
In FIGS. 4 and 5 there is shown a mechanism for bringing the heavy, rapidly
moved sheet stacks 23 and 56 exactly and promptly into a resting position.
For this purpose, a pulse absorber is used in an advantageous manner,
which makes it possible for the sheet stacks 23 or 56 to come to rest free
of energy always at the same place and at any speed, when they push, with
varying force, on the movable masses or stop rods 138-142. A folding blade
enters each sheet stack 23 or 56 at the same point, so that within the
whole speed range, a very exact fold at the highest possible speed is
guaranteed. Even very heavy sheet stacks 23 or 56 can be braked without
any problem. Preferably the suitable pulse absorbing mass 138-142
corresponds approximately to the mass or to the weight of the sheet stacks
23 or 56.
The sheet stacks 23 or 56 are conveyed by means of driven tape guides 32 or
33 to a folding table 105 each of which is equipped with folding rollers
provided below the folding table 105, and with a rotating folding blade.
Every sheet stack 23 or 56 pushes at one of the five stop rods 138-142,
which are movably supported in a brake drum 110 and are pressed into a
resting position on the periphery of the brake drum 110 by means of
springs or torsion bars 121-125. The stop rods 138-142 are disposed at
right angles to the direction of motion of the sheet stacks 23 or 56
respectively, and in such a manner that the sheet stacks 23 or 56 push
with their face 109 at the stop rods 138-142 and are capable of moving
said rods from their resting position. In order to avoid the sheet stacks
23 or 56 being moved beyond the folding table 105, or opening at their
face 109, U-shaped stops 136, 137 are fixed at the end of the folding
table 105.
The brake drum 110 is moved by means of an intermittent drive, for example
a Maltese cross gear in such a manner that the brake drum 110 stops
instantaneously for the period in which a sheet stack 23 or 56 pushes at a
movable stop rod 138-142. After this push, the stop rod 138-142 moves
against the increasing spring pressure into the center of the brake drum
110, while the brake drum 110 is simultaneously rotated incrementally to
the following resting position. Therefore, a pushed mass, for example in
the form of stops rods 138-142, is immediately moved out of the reach of
the sheet stack 23 or 56, and is thus not capable of touching and
displacing said sheet stacks 23 or 56 again when it swings back.
Furthermore, it is an advantage that the pushed mass 138-142 has
sufficient time to get to a relative rest position with respect to the
brake drum 110 again, since four further sheet stacks 23 or 56 are being
stopped by other identical movable masses 138-142. Thus, very high
operating speeds of the whole system can be obtained.
FIGS. 4 and 5 show a preferred cage-like structure of the brake drum 110. A
shaft 112 is rotated by steps of one-fifth rotation each. On shaft 112,
two side flanges 113, 114 each provided with five borings or notches are
disposed on a circle with radius "r". Hollow shafts 116, 117, 118, 119,
120 with internal torsion bars 121, 122, 123, 124, 125 are rotatably
supported in these borings. Hollow shafts 116-120 carry light supporting
arms 126-135, the supporting arms carrying the stop rods 138-142. Stops
143-147 provided on the side flanges 113, 114 limit the oscillating stroke
of the stop rods 138-142. The arriving sheet stack 23 or 56 pushes, in
accordance with its kinetic energy, more or less violently at the stop
rods 138-142 and is caused to rest, free from energy, on the folding table
105. FIGS. 4 and 5 show a cross sectional view of the brake drum 110. They
show the shaft 112 supported in side frames 153, 154 and equipped with the
side flanges 113, 114 and the rotatable hollow shafts 116-120. The
supporting arms 126, 127; 128, 129; 130, 131; 132, 133; and 134, 135
support the stop rods 138-142 as mass pendula. The stop areas 148-152 on
the stop rods 138-142 are spaced in the resting position at a distance "a"
from an axis of rotation 166 of the brake drum 10.
FIGS. 4 and 5 also show a drive system for incrementally rotating the brake
drum 110, which is very simple in spite of its high efficiency of, for
example, 45,000 stoppages per hour. A Maltest cross gear 155, having five
slots 156-160, is secured on the shaft 112. A driving plate 161, supported
in the side frame 153 carries three driving rollers 162, 163, 164
staggered at 120.degree. from each other, which enter into the slots
156-160. The remaining angle of rotation left between the slots of
.+-.6.degree. is covered by circular arc-shaped extensions of the slots
156-160, so that the driving rollers 162-164 serve also as mutually acting
blocking rollers during the short rest of the Maltese cross gear 155. An
identical driving system is described in detail in German Pat. No. 17 61
074, serving, however, another purpose. The power input on the Maltese
cross gear 155, 161 is done by means of a gear 165, which is in functional
conjunction with a drive of the folder. In this case, also a side flange
113, 114 may be designed as a Maltese cross gear 155.
It is possible to install more or less than five movable masses 138-142 in
the brake drum 110. It is also not required that these movable masses be
moved as pendula around a synchronizing center of rotation, but they may
be designed as masses running in straight-line guides. Instead of the
torsion bars 121-125, other immobilizing means and supplementary shock
absorbers may be provided. The pulse absorbing drum 110 is not restricted
to its application in the second longitudinal fold in a rotary folder, but
it may be used in general where rhythmically conveyed sheet stacks, or
books, or the like are to be abruptly braked.
While preferred embodiments of a folder for a web-fed rotaty printing press
in accordance with the present invention have been set forth fully and
completely hereinabove, it will be obvious to one of skill in the art that
changes can be made, for example, as set forth in the preceding paragraph,
without departing from the true spirit and scope of the present invention
and that accordingly, the invention is to be limited only by the appended
claims.
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