Revolving table for book-binding stackers and the like

An improved revolving table intended for stackers as utilized in book-binding shops and the like, has a pusher reciprocating arrangement which is accommodated in the table structure, the pusher being, at its travel limit positions, located on the surface of the revolving table. The table is formed with a slot in the diametrical direction, and has, depending therefrom, a hollow beam accommodating the pusher reciprocating arrangement. For a given stack size, lower bulk dimensions can be achieved for the stacker.

BACKGROUND OF THE INVENTION 
This invention relates to an improved revolving table for book-binding 
stackers and the like. 
As is known, stackers are machines positioned downstream of book-binding 
equipment, such as collators, where they function to form stacks of 
sheets, signatures, pamphlets, brochures, or the like, upon arrival from 
said book-binding equipment. 
Since, in the instance of brochures or signatures, the same would have a 
back or spine side which assumes a larger thickness dimension along the 
fold side than the remaining portions of the brochures or signatures, in 
order to avoid the formation of fanned-out, and consequently unstable, 
stacks, it is common practice to lay the stacks onto a revolving table 
which can be rotatively reciprocated through 180 degrees and, upon the 
formation of each single layer in the stacks, is rotated by 180.degree. to 
form the next layer. Arranged orthogonally to the direction of arrival of 
the signatures or the like, a conveyor belt is associated with the system 
for the removal of the completed stacks. To transfer the stacks from the 
revolving table onto the stack removing conveyor belt, in a conventional 
construction, a cylinder-piston unit is associated with the stationary 
stacker frame, the free end of the piston rod whereof has a pusher secured 
thereto, which pusher is, in its inoperative or home position, located in 
front of the revolving table, substantially on the same plane as the 
table. 
Said cylinder-piston unit extends in the direction of movement of the stack 
conveyor belt and sticks out of the stacker frame in cantilever 
relationship therewith. 
The pusher performs its movements on the revolving table. 
Such prior stackers have several deficiencies and disadvantages, among 
which the following stand out. 
(a) The stacker bulk dimensions are increased considerably by the provision 
of the cantilevered cylinder-piston unit for actuating the pusher. This 
entails increased space requirements in a book-binding environment where, 
as is well known, space is at a premium and not always available. 
(b) Since the pusher is external to the revolving table and separate from 
it, the result is that the revolving table must be allowed fairly large 
overall dimensions to prevent the pusher, while stationary, from 
interfering with the stack corners during the table rotation. This 
reflects, on one hand, in a further increase of the stacker size, and on 
the other hand, in the need for a longer stack-ejecting stroke of the 
pusher. 
(c) Upon completion of the stack-ejecting stroke, the pusher must be 
returned to its initial position, before another stack-ejecting stroke can 
take place. Therefore, each stack-ejecting stroke is followed by an idle, 
that is inactive, stroke. This, of course, considerably reduces the number 
of stack-ejecting cycles per unit time. 
(d) It is only possible to eject the stacks in one direction, that is in 
the pusher direction of movement. This involves the use of a single 
conveyor for stack removal, whereas in many cases it would be desirable to 
use two or more stack conveyor belts set at an angle to each other, e.g. 
at 90.degree. or 180.degree.. 
(e) The procedure for adapting a stacker to its associated book-binding 
machine, e.g. a collator, or to get the oncoming stacks aligned, requires 
several manual operations and a number of movable parts. 
SUMMARY OF THE INVENTION 
This invention is directed to provide an improved revolving table, as 
indicated, which can obviate the aforementioned disadvantages. 
This object is achieved, according to the invention, by an improved 
revolving table for book-binding stackers and the like, having a means for 
driving said table rotatively, a pusher movable to eject stacks and 
associated therewith a means for driving said pusher, and conventional 
movable stack positioners, characterized in that said pusher is supported 
on said table for reciprocation between two travel limit positions located 
on the surface of said revolving table, there being preferably provided 
pusher guiding means and a means for reciprocating said pusher preferably 
incorporated with said table, and a means for step rotating said table. 
The proposed solution affords the advantage that each stroke of the pusher 
can be a useful stack ejecting stroke, as well as the advantage of 
considerably reducing the bulk dimensions of the stacker with respect to 
conventional stackers having the pusher actuating cylinder-piston unit 
associated externally to the stacker in cantilever relationship therewith. 
A further important advantage afforded by the proposed solution is that, 
for ejecting the stacks, one or more of the stacker three sides may be 
utilized as desired, with the sole exception of the side receiving the 
signatures from the collator, or the like machine. 
Yet another advantage of this improved revolving table is that the table 
can be accommodated in existing stackers, with but a few alterations. 
Furthermore, through the solution herein proposed, it becomes possible to 
considerably increase the stack ejection speed, which reflects in the 
possibility of operating the feeding machine, such as a collator, at its 
optimum speed for an improved output of the same. This is made possible by 
that the pusher is always located within the table structure, thereby a 
shorter stroke is required for the ejection. Moreover, for a given maximum 
size of the stack, with the inventive solution, the table can be made 
smaller than conventional ones, because the pusher, which in accordance 
with the invention is positioned on the table, can now occupy a surface 
portion of the table left free by the stack, so that it is prevented from 
hitting the corners of the stack itself while the latter, or the table, is 
being rotated. 
An additional advantage of the invention is to be found in the simple and 
quick effectuation of the signature or the like centering operations, 
since it will be sufficient to shift the table horizontally without 
manipulation of the pusher or actuating means therefor.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
With reference to the drawing figures, where similar parts have been 
designated with the same reference characters, the improved revolving 
table of this invention is generally indicated at 1. It comprises a table 
body 2, which in the embodiment shown, is a single-piece casting. Said 
body 2 is formed with a diametrical throughgoing slot 3 and provided, at 
the bottom and juxtaposed to said slot 3, with a hollow beam 4 extending 
parallel to the slot 3 across the axis of the table body 2 and having 
windows 4a for lightening purposes. Located transversely to the beam 4, on 
the bottom side of the table body 2, are opposed lateral surfaces 5, which 
will be described hereinafter. Through the body 2, and centrally with 
respect to said lateral surfaces 5, there are formed two diametrically 
extending slots 6, through which slots are passed respective strip 
supports 7 for a movable side stack locator or positioner, indicated at 8. 
The positioner 8 and related support and driving means accommodated 
between the lateral surfaces 5 are no further described herein, because 
known per se and foreign to this invention. 
The pusher is indicated at 9. The means for reciprocating it comprises, in 
the embodiment shown in FIGS. 1-3, a cylinder-piston unit 10 carried 
within the beam 4 and extending in the direction of the beam 4. The unit 
10 has a flexible drive element, such as a rope-like one, which is passed, 
at the two ends of the unit 10 adjacent the ends of the beam 4, around 
rotatably supported end pulleys 12 and connected, with its free ends, to 
the piston ends, in a manner no further illustrated. The movement of the 
piston will cause a corresponding displacement of the drive rope 11, to 
which rope there is attached, such as by means of a screw-actuated 
fastening element 13, a tubular projection 14 which is integral with the 
pusher 9 and slidable on a guiding rod 15, the latter extending within the 
slot 3 parallel thereto and being supported on end plates 16 fastened, 
with screws 17, to the hollow beam 4 at the ends thereof. The reference 
numeral 18 designates rolling wheels mounted laterally to the pusher 9. 
On the bottom side of the hollow beam 4, the latter is provided with a 
projection 19 acting as a stop element cooperating with fixed stop 
elements 20,21 for limiting the table rotation and being known per se and 
only shown schematically. These will be equipped with conventional shock 
absorbing elements, not shown. In the embodiment being considered, the two 
stops 20,21 allow for a rotational reciprocation of the table 1 through 
180 degrees in normal operation. The table is rotatively driven, in this 
embodiment, by means of a conventional cylinder-piston unit 22 which is 
supported on the stacker stationary frame, and has a gear segment in mesh 
engagement with a pinion keyed to the shaft of the revolving table 1 in a 
manner known per se and no further illustrated. 
The reference numeral 23 designates a rotating cylindrical distributor 
arranged centrally of the table 1 below the cylinder-piston unit 10 and 
the beam 4 for supplying compressed air to the cylinder-piston unit 10. 
The distributor 23, which is coaxial to the table body 2, may be of any 
selected types. 
In the exemplary embodiment illustrated, there is indicated at 9a in FIG. 1 
a strip projection of the pusher 9 which forms the tubular portion 14 at 
its free end. At 24 are indicated two conventional guiding rod-like 
elements which are secured to the top side of the table body 2 along the 
longitudinal edges of the slot 3 for the purpose of imparting, to a stack 
being formed, a slightly sagging configuration effective to facilitate the 
ejection of the stack. The pusher 9 is provided with corresponding 
depressions or seats 25 for riding on the rod-like elements 24. The pusher 
is advantageously a hollow, or perforated, construction of 
parallelepipedal shape for lightening purposes. 
By providing advantageously, instead of the cylinder-piston unit 22, a 
stepped motor associated with a programming unit, it becomes possible to 
selectively rotate the table 1 in accordance with a desired stack ejection 
program. 
The operation of the improved revolving table of this invention will be 
readily appreciated from the foregoing description. 
After a stack has been formed, the pusher 9 will provide for the ejection 
of the stack by actuation of the cylinder-piston unit 10. The movement of 
the piston of said unit 10 produces a corresponding displacement of the 
rope drive element 11, and accordingly, of the pusher 9 across the axis of 
the table body 2. Upon completion of an ejection stroke, the formation of 
a fresh stack can be immediately initiated without completing any prior 
idle return stroke of the pusher 9. After completion of a stack, if the 
latter is to be ejected in the opposite direction to the direction of 
ejection of a preceding stack, it will be sufficient to actuate the unit 
10 and produce the ejection stroke of the pusher 9. Where, instead, the 
stack is to be ejected in the same direction as the preceding stack, the 
table is rotated, with a quickly effected operation, through 180.degree., 
whereafter the stack ejection stroke can take place. Whether, on each 
occasion, a 180.degree. rotation or the effectuation of an idle return 
stroke (which would in all cases be shorter than with prior machines) may 
be more appropriate, is a decision which will depend on the speeds of 
rotation of the table and displacement of the pusher specifically 
attainable. 
By providing, instead of the unit 22, a stepped motor and associated 
programming unit, which components are individually well known in the art, 
it becomes possible to effect each time any desired step rotation 
movements and to eject the stacks along different selected directions 
angularly related to one another. 
In the modification of FIG. 4, the means for reciprocating the pusher 9 
comprises a closed-loop chain 11 run around two sprocket wheels 26 and 
driven by a sprocket 27 that is rotated by an electric motor, or rack and 
pinion device, or pairs of driving wheels with intervening friction 
clutches, or the like, in quite a conventional manner no further discussed 
herein. The reference numeral 28 diagrammatically designates a 
counterweight attached to the chain 11 for balancing the pusher 9 as the 
table is being rotated. In fact, when the pusher 9 is in the position 
shown by full lines in FIG. 4, the counterweight 28 is in the position 
shown by full lines, i.e. substantially diametrically opposite to the 
pusher 9 such as to balance the centrifugal force acting on the pusher 9 
during rotation of the table 1. A similar balancing action occurs when the 
pusher 9 and counterweight 28 are in the positions shown by dotted lines. 
The closed-loop chain 25 could obviously be arranged to lay in a vertical 
rather than horizontal plane. 
It will be appreciated from the foregoing that the invention achieves its 
object in a most effective way, and that the advantages specified in the 
preamble can be achieved. In particular, the construction is simplified, 
dimensions are reduced, and the operating speed is increased. 
Substantial to the invention is the provision for the pusher of stroke 
limit positions on the table itself. In practicing the invention, 
individual parts may be replaced with other technically and functionally 
equivalent parts; thus, for example, for the guiding element of the pusher 
9, a single profile section rod, or two parallel rods, may be provided, 
etc., without departing from the true scope of the invention. 
Furthermore, the pusher driving means may be provided in the form of a rod 
type of drive element adapted to engage with the upper portion of the 
pusher 9. 
While the table body 2 has been described as formed by casting, the same 
may also be constructed as an assembly of separate parts connected 
together, such as by welding.