Method and apparatus for aligning a pile of sheets provided with perforations for bindings

For aligning the binding perforations of a pile of sheets, straight prongs are inserted in the perforations and, during their withdrawal, are moved in non-positive manner in the direction of a curved shaped surface, so that the tip area of the prongs presses the back of the pile against the shaped surface and consequently the desired curved shape of the perforation is obtained.

The invention relates to a method and to an apparatus for aligning a pile 
of sheets provided with perforations for bindings, in which prongs are 
introduced into the perforations and the back of the pile is pressed by 
them against a curved shaped surface. 
Piles of sheets often are bound together in so-called spiral or comb-like 
bindings, which have binding elements made from wire or plastic, whose 
turns or portions pass through the perforations. Piles thicker than a 
certain minimum thickness must be so prepared for binding purposes that 
the perforations, which after punching form a linear channel, have a 
curvature approximately corresponding to the helical curvature or the 
curvature of the individual portions of a comb-like binding, in order that 
a frictionless insertion of the binding in the perforations is ensured. 
German Offenlegungsschrift No. 29 52 183 discloses an apparatus, in which 
alignment takes place by pressing the pile of sheets on to a curved shaped 
surface by means of straight prongs, which are inserted from both sides 
into the perforations and then moved out again. When the prongs are moved 
out they are tilted in accordance with the curvature, so that they also 
engage the outer areas of the back of the pile of sheets with the shaped 
surface. This procedure requires a very complicated mechanical gear, which 
must be precisely set to the desired curvature or sheet pile thickness, in 
order that there can be no tilting of the prongs in the perforations. 
German Patent 18 17 815 discloses an apparatus, which operates with a 
shaped surface and curved prongs operating in opposite directions, but 
here again they must be adapted in accordance with the curvature. 
The object of the present invention is to provide a method and an apparatus 
for aligning a pile of sheets provided with perforations for bindings, 
which operates simply and reliably and can be easily adapted to different 
circumstances. 
According to the invention, this object is achieved by a method in which, 
starting from the center, the sheets are successively pressed against the 
shaped surface by the tip area of the prongs, displaced in a parallel 
alignment or manner in the direction of the shaped surface when they move 
out of the perforations. 
Thus, the prongs do not have to be tilted about an axis parallel to the 
back of the sheets. Instead, the prongs are moved out, accompanied by a 
simultaneous movement in the direction of the shaped surface and "copy" 
the configuration of the shaped surface of the inner wall of the 
perforation directed towards the back. 
The adjustment of the apparatus to different back curvatures, etc. is 
particularly simple, if pressing takes place in a non-positive manner, 
"non-positive" meaning in a resilient fashion providing for "give," as 
opposed to a positively-driven fashion in which the prongs would be forced 
to travel a fixed path having no provision for resilient deviation 
therefrom. In this case, the extension movement and the movement in the 
direction of the sheet back need not be precisely matched to one another. 
For example, during the forcibly controlled extension of the prongs, there 
can be a spring loading in the direction of the back of the sheet, which 
ensures the necessary pressing action. 
In the case of spiral bindings, in which the wire coil to be turned into 
the perforations has a pitch, it is also necessary to align the 
perforations in accordance with this pitch. Whereas this was frequently 
previously carried out by external stops on the sides of the pile of 
sheets, it is possible here to carry this out without additional measures 
by inclining the prongs prior to their extension. 
Thus, in the apparatus according to the invention, the prongs are provided 
on an insertion and removal device. The device is operable for inserting 
the prongs into the perforations and for the parallel removal thereof, 
while a pressing device being provided for moving the prongs in the 
direction of the shaped surface. 
Preferably the straight prongs are aligned substantially perpendicularly to 
the pile of sheets when viewed longitudinally along the back. 
On at least one edge associated with a thicker cover sheet in the pile of 
sheets, the rounded shaped surface advantageously has a recessed portion 
to receive the cover sheet and otherwise corresponds to the rounding of 
the back. This ensures that the cover sheet with its external perforation 
edge follows the curve formed by the inner faces of the bore pointing 
towards the back. Otherwise this outer edge of the cover sheet would 
project inwards somewhat and would, in certain cases, disturb the 
introduction of the spirals. 
On both its upper and lower sides the shaped part can have comb-like guide 
portions, preferably provided with feed slopes, projecting over the shaped 
surface toward the pile. These guide portions can be linked laterally with 
the recessed portions such that the prongs pass through the slits between 
teeth of the comb-like configuration. These guide portions ensure that the 
pile of sheets, which cannot be secured during its alignment, does not fan 
out in this area. 
Advantageously the prongs engaging different perforations from either side 
of the pile can be mechanically coupled together in their extension and 
advance movement. Thick sheet piles are frequently punched in several 
different layers. Should one layer be incorrectly punched, for example the 
perforation distance from the back being less than required, then the 
coupled copying movement of the prongs on either side still aligns the 
perforations in a precise arc. In such as case, the incorrectly punched 
sheet layer is not moved right up to the shaped surface, because the prong 
is controlled by the correctly punched sheets resting on the other layer. 
The advantage resulting from the parallel guidance of the prongs during 
insertion and removal, is made particularly apparent if the apparatus is 
used for spiral bindings, where it is preferable for the prongs to be in 
each case pivotable about an axis with substantially the same angle, 
whereby said axis runs parallel to the pile and at right angles to its 
back. Otherwise there would be several reciprocally superimposing pivoting 
movements, which would be mechanically very difficult to realize. A 
relatively simple and reliable embodiment to manufacture provides that the 
prong holders carrying the prongs form part of a parallelogram guide. 
These parallelogram guides for the two rows of prongs can be provided on 
oppositely controlled rails. This makes it possible to simultaneously 
bring all the prongs into their inclined position as required to trace the 
pitch of spiral bindings and also to carry out the coupled, oppositely 
directed movement.

A pile 1 of sheets is provided along its back or binding edge 50 with 
numerous juxtaposed, linear perforations 51 arranged in a row, for 
alignment. The pile is supplied at right angles to the drawing plane of 
apparatus 3 in FIG. 1, by means of a toothed belt, which can grip or 
release the pile between it by clamping. Upper and lower prongs 4, 5 are 
used for alignment purposes and comprise linear pins, which are also round 
in the case of round bores, with rounded, pointed, free ends. They are 
fixed in blocks 6, 7, which are adjustably screwed to prong holders 9, 10 
by means of slots 8 (FIG. 2). In each case, the prong holders 9, 10 are 
pivotably fitted to two superimposed, horizontally directed ledges 11, 12 
(for upper prong holder 9) and 13, 14 (for lower prong holder 10), whereby 
each ledge pair 11, 12 and 13, 14 forms a parallelogram guide. 
The ends of the upper ledges 11, 12 are pivotably fitted to externally 
moving guide rails 15, 16 (FIG. 2), while each of the lower ledges 13, 14 
is pivotably fitted by its end to inner guide rails 17, 18. Thus, with 
guide rails 15 to 18 and prong holders 9, 10, ledges 11 to 14 form a 
double, partly telescoped parallelogram, in which the prong holders 9, 10 
form the pegs of a horizontally arranged ladder, whose superimposed cross 
members are displaceable relative to one another. 
FIG. 2 shows that the guide rails 15 to 18 are so coupled together by 
pinions 19 and corresponding racks 20 on the guide rails, that they have a 
very precise opposite-sense movement during reciprocal displacement in 
guides 21. The guides provided at the top and bottom for the two carrier 
ledge pairs are in each case fixed to carriers, which are rotatably 
mounted by means of, in each case, one central, horizontal spindle 23, on 
a horizontal reciprocable slide 25 extending at right angles to the 
extension of the sheet pile back. An adjustable stop 36 limits the side 
movement. 
The movement sequences of this mechanism are driven from a common 
synchronous shaft for the complete apparatus, which can e.g. be driven by 
a motor via a gear, and which drives cams 26, 29, 32. 
FIG. 1 shows that the movement of slide 25 is controlled by means of a 
double-armed lever 28 and a connecting rod 27, as well as a lever 24 with 
a roller running on cam 26. A spring 35 loads the mechanism in such a way 
that the roller 53 is resiliently biased toward cam 26. Thus, it forms a 
resilient loading of the slide in a left-directed movement direction, 
which is limited by cam 26. 
In the position shown in FIG. 1, the slide 25 is in its right-hand end 
position, in which the perforated sheet layer 1 is drawn into its 
alignment position with the upper conveyor belt 2 raised, by the insertion 
of prongs 4 and 5 into the perforations. The opposite-sense, coupled 
insertion of prongs 4, 5 into perforations 51 is controlled by cam 29 
(FIG. 2), which by means of a linkage including angular lever 30 and a rod 
31, moves the guide rail 15 downwards. Simultaneously, by means of rack 20 
and pinion 19, a precisely oppositely directed upward movement is imparted 
to guide rail 17, so that the two prongs, which are oppositely directed, 
can each be inserted in guided manner into a stack of aligned 
perforations, the pins being inserted into neighboring holes, displaced 
relative to one another by one spacing. A coupling mechanism between the 
right-hand rack 15 and the left-hand rack 18 is provided, but is not shown 
in order not to overburden the drawing. 
For using the apparatus for products provided with a spiral binding, a 
sloping device is provided for prongs 4, 5, which comes into action when 
the prongs are inserted into the perforations. It gives the perforations a 
sloping alignment in a plane parallel to the back, corresponding to the 
pitch of the wire coil to be helically-inserted into the perforations 
adjacent the back. For this purpose cam 32 shown in the right-hand half of 
FIG. 2 is provided, which by means of a lever 33, can pivot carrier 22 
about spindles 23. The two carriers are coupled together in 
parallelogram-like manner by means of guide rails 15 to 18 and ledges 11 
to 14, so that by means of their prong holders 9, 10, the prongs are all 
aligned in parallel, sloping manner to one another. 
When using the apparatus for wire comb-like bindings, in which the portions 
engaging in the perforations have no slope or pitch in the direction along 
the back, the cam 32 can be disengaged and optionally spindles 23 can be 
blocked in slide 25. 
The cooperation between cams 26 and 29 brings about the control of the 
alignment of the pile of sheets relative to the curvature of the 
perforation channel, corresponding to the curvature of the wire coil or 
comb-like binding to be turned in. Whilst cam 29 imparts to the prongs a 
preferably uniform extending movement out of perforations 51, a movement 
to the left in FIG. 1 is additionally imparted thereto, so that the prongs 
press the back of the sheet layers against a shaped surface 54. Shaped 
surface 54 is provided on a shaped part 34, which can comprise individual 
shaped blocks. Cam 26 is constructed in such a way that on pressing the 
prongs in the direction of the shaped surface 54, there is always a 
certain clearance between the cam 26 and cam roller 53. The pressing force 
is applied by tension spring 35 and cam 26 is operative only beyond a 
certain displacement. Thus, pressing takes place in a resilient manner 
rather than a positively-driven manner. Setscrew 36 forms the end stop in 
the movement of the movable apparaus part to the left. 
The alignment method will now be described in detail relative to FIGS. 3 to 
6. 
The shaped part provided on a fixed part of the machine, i.e. not movable 
with respect to the previously described mechanism, has on its end 
pointing towards the back 50 of the pile of sheets, a moulded surface, 
which is generally a circular cylindrical surface with a horizontal 
orientation. It is bounded on either side by guide portions 37 projecting 
in the direction of the pile and which are constructed in comb or 
fork-like manner. Prongs 4 and 5 project into slits 40 between the tines 
or teeth of the guide portions. The tines have an insertion slope 41. In 
the area adjacent to the shaped surface, the guide portions have bearing 
surfaces 42, which roughly correspond to the pile thickness. For a pile 
having thicker cover sheets, slot-like portions 43 are provided on either 
side of the shaped surface 54 and correspond approximately to the cover 
sheet thickness. 
FIG. 3 shows the straight prongs 4, 5 inserted into the straight holes and 
as a result pile 1 is brought into engagement with the shaped surface 54. 
After optionally sloping the prongs in accordance with the right half of 
FIG. 2, the prongs are now extended in the direction of arrows 38 in FIG. 
4, whereby said prongs always remain at right angles to the plane of the 
pile, in the view shown in FIGS. 3 to 6, i.e. viewed along the pile back 
50. Simultaneously the prongs are moved in the direction of arrow 39, 
under the action of spring 35, which is put into operation as a result of 
the fact that in this operating phase, cam 26 faces cam roller 53 with its 
recessed portion, so that there is a certain clearance between cam 26 and 
cam roller 53. 
FIG. 4 shows that prongs 4, 5 are positioned such that their tip area is in 
contact with the inner faces of the bore defined by the stacked 
perforations, on a side facing the back 50. The resiliently-biased prongs 
start to move the sheets in the direction of sheet surface 54 in a 
successive manner as the prongs are withdrawn, starting from the center, 
i.e. the point located furthest right. The perforation channel initially 
only has a curved form in the central area and for the moment maintains a 
straight form in the area in which the prongs are still located, although 
the corresponding sheets have already been moved up. It is clear that the 
spherically chamfered tip form of the prongs is very advantageous, because 
it ensures a substantially flat engagement. It is also clear that in this 
operation, the prongs can have a significant thickness and the diameter 
thereof can almost correspond to that of the perforations, although they 
leave behind a very significantly curved bore. As a result the prongs are 
very stable and can transfer very considerable alignment forces. 
Particularly if the prongs align the outer area of the pile, guide portions 
37 and in particularly surfaces 42, prevent fanning out of the pile during 
alignment. 
In FIG. 5, alignment is almost complete. Finally, the two cover sheets 55 
are moved along both sides of the pile and then prongs 4, 5 are retracted 
from the stack. The prongs are extended upwards and downwards, without any 
further horizontal movement, once slide 25 engages with stop 36. 
FIG. 6 shows a detail of the aligned pile of sheets. It can be seen that as 
a result of the recessed portion 43, cover sheet 55 can be moved somewhat 
more than would correspond to the normal curvature of shaped surface 54. 
As a result the upper edge of the cover sheet facing back 50 has been 
placed along the finished curve (broken line 56), so that an entering 
spiral on this side, which is critical during insertion, finds an open 
perforation. The resulting edge on the opposite side is not a problem upon 
spiral binding. Following on the extension of the prongs, the pile 1 is 
taken up again by the clamping together of toothed belt 2 and is conveyed 
in aligned form to the binding station. 
Numerous modifications of the represented embodiment are possible within 
the scope of the invention. In place of a pressing movement of the prongs 
against the shaped surface, the shaped surface could be moved against the 
pile of sheets or the prongs. In place of spring 35, it would also be 
possible to use e.g. a pneumatic device or a weight for bringing about the 
necessary resilient and non-positive force closure. Normally it is 
advantageous to provide a prong, entering from above or below, for each 
perforation, particularly this permits the removal of any punching waste 
from the bores. However, it would also be possible to provide a smaller 
number of prongs, because even fewer prongs still have an adequate 
alignment action,