Apparatus for forming partial stacks from printed sheets standing one behind the other

An apparatus for forming partial stacks by separation of a stack of printed sheets standing one behind the other includes an approximately horizontal stack guide having a feed end for receiving printed sheets fed in a direction perpendicular to the stack guide from a feeding apparatus and stacking the printed sheets on edge to form a stack in a horizontal direction. A separating device is arranged along the horizontal stack guide for forming the partial stacks. The separating device includes a guide arrangement disposed parallel to the horizontal direction of stack forming. First and second components of the separating device are seated one behind the other on the guide arrangement and are displaceable along the guide arrangement. The first and second components are jointly displaceable to the feed end of the stack guide and are controllable to be separable from one another in a stack separating position. Spreading elements are pivotally connected to the first and second components of the separating device. The spreading elements are displaceable jointly with the first and second components to the feed end of the stack guide. Support elements each associated with a respective one of the first and second components of the separating device are driven into the stack of printed sheets between the spreading elements for separating the spreading elements from one other between two printed sheets thereby keeping the two printed sheets apart from one another and forming the partial stacks of printed sheets.

BACKGROUND OF THE INVENTION 
The invention relates to an apparatus for forming a partial stack through 
the separation of printed sheets, which partial stack extends 
perpendicularly with respect to the printed sheets standing one behind the 
other, which apparatus is connected downstream of a feeding apparatus 
conveying the printed sheets in a preferably imbricated formation 
approximately perpendicularly to the direction of stack forming and which 
is provided with an approximately horizontal stack guide along which a 
multi-component separating device is arranged, which is intended for 
forming the partial stacks and which can be powered, which components of 
the separating device, are each provided with spreading elements of a 
spreading apparatus keeping the printed sheets apart in proximity of the 
stack guide, which spreading elements plunge between two printed sheets 
which follow one another fold forward, of which spreading elements the 
spreading element that is leading in the direction of stack forming is 
associated with the rear end of a formed partial stack and the trailing 
spreading element is associated with the front end of a subsequent stack 
of printed sheets or partial stack, and with which spreading elements a 
support element of a support apparatus is associated which support element 
can be driven into the stack of printed sheets between the spreading 
elements keeping the printed sheets apart from one another. 
An apparatus of the type described above is disclosed in European patent 
application EP-A-0 623 542. 
A principal demand with respect to an apparatus of this type is the 
reliable and damage-free separation of the printed sheets between two 
partial stacks to be formed which are first transported and deposited for 
intermediate storage or which, immediately afterward, are separated again 
during further processing. 
SUMMARY OF THE INVENTION 
It is an object of the invention to provide an apparatus with which, in a 
simple manner, precise separating conditions between two printed sheets of 
a stack can be accomplished for forming partial stacks. 
The above and other objects are achieved according to the invention by the 
provision of an apparatus for forming partial stacks by separation of a 
stack of printed sheets standing one behind the other, comprising: an 
approximately horizontal stack guide having a feed end for receiving 
printed sheets fed in a direction perpendicular to the stack guide from a 
feeding apparatus and stacking the printed sheets on edge to form a stack 
in a horizontal direction; a separating device arranged along the 
horizontal stack guide for forming the partial stacks, the separating 
device comprising: a guide arrangement disposed parallel to the horizontal 
direction of stack forming; first and second components seated one behind 
the other on the guide arrangement and being displaceable along the guide 
arrangement, the first and second components being jointly displaceable to 
the feed end of the stack guide and being controllable to be separable 
from one another in a stack separating position; spreading elements each 
pivotally connected to a respective one of the first and second components 
of the separating device, one of the spreading elements being a leading 
spreading element, with respect to the direction of stack forming, and 
another of the spreading elements being a trailing spreading element, the 
spreading elements keeping the printed sheets apart in proximity of the 
stack guide by projecting between two printed sheets which follow one 
another, the leading spreading element being associated with a rear end of 
a formed partial stack and the trailing spreading element being associated 
with a front end of a subsequent stack of printed sheets, the leading and 
trailing spreading elements being displaceable jointly with the first and 
second components to the feed end of the stack guide; and support elements 
each associated with a respective one of the first and second components 
of the separating device for being driven in the stack separating position 
into the stack of printed sheets between the spreading elements for 
separating the spreading elements from one other between two printed 
sheets thereby keeping the two printed sheets apart from one another and 
forming the partial stacks of printed sheets. 
Thus, according to the invention the spreading elements of the separating 
device can be displaced in a joined manner to the feeding end of the stack 
guide by means of a mutual approach of the components of the separating 
device, which components are seated one behind the other on the guide 
arrangement that is parallel to the direction of stack forming. Further, 
the spreading elements can be separated from one another in the stack 
separating position between two printed sheets by means of the support 
elements which can be driven into the stack of printed sheets. 
Thus, the functions necessary for forming partial stacks can be executed 
along the stack guide in defined relationships, so that clear sequential 
conditions can be generated. 
Further objects, features and advantages of the invention will become 
apparent from the following detailed description of the invention when 
considered in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION 
FIGS. 1 to 9 illustrate in sequence the production of a partial stack 1 
from a stack 3 of printed sheets 2. FIG. 1 illustrates an initial position 
in which a two-part separating device 4 is disposed on a return path into 
an initial position. Printed sheets 2 stand on their fold 7 one behind the 
other on a stack guide 5, which is indicated here by a dash-dot line and 
which is formed by a pulling means 32 (shown in FIGS. 10 and 11), for 
example, endlessly circulating toothed belts, and stationary guide strips. 
The stack 3 of printed sheets is formed by a feeding apparatus 6. Printed 
sheets 2 arrive in an imbricated formation at a feeding end 8 of stack 
guide 5. Stack forming takes place from feeding end 8 toward the right. 
A front end 9 of stack 3 of printed sheets 2 rests against an end plate 10, 
which delimits a front end of a later formed partial stack 1. End plate 
10, in turn, rests against one of two clamping elements 12, 13 of a 
pressing apparatus 11 and is slidingly supported on stack guide 5. 
The apparatus of the invention would also permit feeding of printed sheets 
from below to a stack guide arranged above the printed sheets. 
Pressing apparatus 11 grasps a partial stack which has a predeterminable 
length and presses it together in a banding station (not shown) following 
the stack forming section or on the way to a banding station. 
FIG. 1 additionally shows units 15, 16 of two-part separating device 4, 
which units are disposed on a guide arrangement 14 in the return travel 
mode along stack guide 5. For this purpose, each unit 15, 16 is comprised, 
respectively, of a spreading element 17 or 18 of a spreading apparatus 19, 
and a support element 20 or 21 of a support apparatus 22. Units 15 and 16 
are disposed below stack guide 5. 
Units 15, 16, additionally include carrier frames 25 and 26, respectively, 
which are slidably guided by way cylindrical liners (not shown) on 
parallel rails 23, 24 of guide arrangement 14 (see also FIGS. 10 and 11). 
Carrier frames 25 and 26 each include an extension arm 27. The two 
extension arms 27 of carrier frames 25 and 26 project with opposite 
orientation along the direction of movement of units 15, 16. A downwardly 
extending piston cylinder unit 28 is fastened to each extension arm 27. 
Each piston cylinder unit 28 is connected to a support 29 at a bottom end 
of the respective carrier frame. Carrier frames 25, 26 each have three 
hump-shaped structures 30, which are disposed transversely to the 
direction of movement and spaced apart from one another. Spreading 
elements 17, 18 are oriented toward one another and are arranged on 
structures in a bearing block 31 in which they are pivotably seated. 
Spreading elements 17, 18 are charged with a restoring force, which is 
active in a downward direction or in a direction oriented away from the 
stack of printed sheets 3. The restoring force can be effected, for 
example, by a torsion spring (not shown) or through gravity. A stop (not 
shown) limits the pivot movement in the downward direction, so that 
spreading elements 17, 18 are kept in a non-active position during their 
return into the initial position at feeding end 8. 
A catch 33, which is connected with the piston of the piston cylinder unit 
28, is connected via an intermediate element 34 to a drive carrier 35 of a 
support element 20, 21 of support apparatus 22. Each support element 20, 
21 includes three support plates distributed over the width of the drive 
carrier 35 and extending approximately to the spreading elements 17, 18. 
In the interest of a gentle advance movement, the ends of the support 
plates oriented toward stack guide 5 are configured to be wedge-shaped 
with respect to width and thickness. Drive carrier 35 of each support 
elements 20, 21 is guided on two spaced guide rods 36, 37 (See FIGS. 10 
and 11) so as to be displaceable, with the ends of the guide rods being 
anchored in the support frame 25, 26 on the one hand and in the support 29 
on the other. 
Because of the relatively wide support surface, support plates 42 to 44 can 
carefully brush over printed sheets 2 that are effected by the advance 
movement. 
During their return into the initial position, units 15, 16 have then again 
reduced the largest distance in the time domain of the end plate 
insertion. 
Movement, both joint and independent, of controlled units 15, 16, is 
accomplished by toothed belts, 38, 39 which are shown schematically by 
dot-dash lines. Toothed belts 38, 39 are arranged to be laterally offset 
with respect to one another. They have an endless configuration and 
circulate around at least one driving roller (not shown). 
In FIG. 2, separating device 4 has reached its initial position, and units 
15, 16 are brought together, with support elements 21, 22 comprised of 
support plates 42 to 44, being disposed opposite one another or are at 
least approximately resting against one another. Spreading elements 17, 18 
are mutually joined during the approach of the units 15, 16 to form an 
element that is standing upright. Spreading element 17 facing the stack of 
printed sheets 3 has a nose-like end, which at least partially covers the 
upright standing end of the other spreading element 18 in order to prevent 
a stage that would hinder the feed flow. Printed sheets 2 which are 
conveyed toward stack guide 5 can slide along the spreading element 18 
without interference, and both spreading elements have a shape which 
excludes any damage to printed sheets 2. Spreading elements 17, 18 each 
have a tooth, flank-like shape oriented toward one another, so that, as 
they set themselves upright, they can stand each other up or roll off on 
each other. In order to reduce wear, the relevant surfaces of the 
spreading elements 17, 18 can be hardened or coated. 
The fact that the stack guide is permanently supplied with printed sheets, 
or that a stack is formed on a continuous basis, is illustrated by a 
comparison of the stack lengths in FIGS. 1 and 2 as well as by the further 
FIGS. 3 to 9. 
In FIG. 2, support elements 20, 21 are in a resting position, but units 15, 
16 are prepared for action. 
In FIG. 3, separating device 4 has been moved downstream into a dividing or 
separating position because a predetermined amount of stacked printed 
sheets 2 for a partial stack 1 has been reached. In this position, 
spreading apparatus 19 rests with spreading element 17 against the 
existing stack of printed sheets 3 before the next printed sheet 2 of the 
imbricated formation reaches stack guide 5 on the opposite side of the 
spreading apparatus 19. This means that, compared to FIG. 2, the position 
of separating device 4 on the guide arrangement 14 has changed. 
Afterward, with a movement of separating element 4 in the same direction of 
stack forming, a new stack 3 of printed sheets is formed opposite partial 
stack 1, on the rearward side of the spreading apparatus 19, as is 
illustrated in FIG. 4. There, separating device 4 is disposed between a 
partial stack 1, which will soon be displaced into a press arranged on 
stack guide 5, and a stack 3 of printed sheets on stack guide 5 which 
continues to get larger. 
In FIG. 5, separating device 4 has reached the separating position on stack 
guide 5, which, among other things, is a function of the selected or 
predetermined length of a partial stack 1, that is, partial stacks 1 of 
different lengths can be created by means of the apparatus according to 
the invention. 
First, support elements 20, 21 of support apparatus 22 are extended on 
separating device 4 which co-circulates so as to increase stack length. 
The upward movement of support elements 20, 21 separates spreading 
elements 17, 18 from one another, so that a distance between the end of 
leading partial stack 1 and the beginning of the subsequent stack 3 of 
printed sheets is generated. 
Of course, matched to the joint motional sequence, spreading elements 17, 
18 and support elements 20, 21 could also be displaced into a desired 
operating position through their own driving means. However, according to 
FIG. 5, this joint motional sequence, wherein spreading elements 17, 18 
produce a greater penetration gap for subsequent support elements 20, 21, 
and their support plates 42 to 44, is effected through driven support 
elements 20, 21 acting on spreading elements 17, 18. 
A control (not shown) initiates a lifting movement of pistons (also not 
shown) of piston cylinder units 28, which in turn lift, via catches 33, 
connecting elements 34 and drive carriers 35, support elements 20, 21. The 
rounded off edges of upwardly moving support plates 42-44, constituting 
support elements 20, 21, push aside spreading elements 17, 18. The 
upwardly moving support elements 20, 21 then plunge between printed sheets 
2 resting against spreading elements 17, 18, enlarging the distance 
between the printed sheets. 
In order to prevent damage to printed sheets 2 that rest against spreading 
elements 17, 18, a recess 40 is provided on support elements 20, 21 
(indicated only in FIG. 5 with dash-dot lines) which makes it possible to 
at least partially receive spreading elements 17, 18, so that the 
frictional pressure on the surfaces of printed sheets 2 produced by the 
spreading elements can be reduced. 
As the size of the stack 2 of printed sheets progresses, FIG. 6 shows the 
installation of an end plate 41 at the rear side of partial stack 1 which 
is moved away from the stack 3 of printed sheets 2 at a greater speed. In 
this position, unit 15 holds partial stack 1 together temporarily via 
supporting plates 42 to 44 until end plate 41 is inserted into a narrow 
gap formed between supporting plates 42 to 44 and clamping element 13. 
Stack forming on stack guide 5 continues without interruptions while all 
these operations and prior operations are performed. 
As shown in FIG. 7, support element 20 of unit 15 has meanwhile moved from 
the aforementioned gap into a resting position below stack guide 5 and 
spreading element 17 has also reached a resting position because of the 
returned support element 20 and the restoring force acting on spreading 
element 17. 
Through compression of printed sheets 2 and through displacement, partial 
stack 1 is now moved into a connected press, controlled in an integrated 
manner, where partial stack 1 is tied or banded with straps and is ejected 
from the machine, as is described in European Patent Application EP-A-0 
623 542. 
Release of clamping element 12 of pressing apparatus 11 and a cohesive 
coordination of all functions of the apparatus according to the invention 
through a control is required in order to accomplish an efficient and 
continuous flow for the uninterrupted, rapid production of partial stacks 
1 from printed sheets 2 that are supplied. As soon as a partial stack 1 
has been compressed and tied with straps, clamping elements 12, 13 of 
pressing apparatus 11 are again available for the insertion of end plates 
10, 41 at the stack ends. Partial stack 1 is ejected from the pressing 
apparatus in a lateral direction, for example, by a bearing surface that 
can be powered. 
The next process step, namely to free unit 16 of the front end of stack 3 
of printed sheets 2, takes place through insertion of an end plate 10 
between support element 21 and returning clamping element 12 of pressing 
apparatus 11. This separating process is illustrated in FIGS. 8 and 9 and 
proceeds as described in the text regarding FIGS. 6 and 7. 
Units 15 and 16 are then controlled to jointly leave the insertion position 
and return to the initial position as shown in in FIG. 2. 
FIG. 10 shows unit 16 of separating device 4 immediately after end plate 10 
has been added to the front end of stack 3 of printed sheets 2, where it 
is disposed in the return path to the initial position (see also FIG. 9). 
FIG. 11 shows the extended position of unit 16 of separating device 4 with 
a view onto the front end of stack 3 of printed sheets 2 (see also FIG. 
6), and pneumatic drive means which are controlled and connected to a 
pressure source. 
The invention has been described in detail with respect to preferred 
embodiments, and it will now be apparent from the foregoing to those 
skilled in the art, the changes and modifications may be made without 
departing from the invention in its broader aspects, and the invention, 
therefore, as defined in the appended claims, is intended to cover all 
such changes and modifications as to fall within the true spirit of the 
invention.