Device for aligning sheets at the front lays of a sheet processing machine

Device for correctly-registered feeding of sheets supplied thereto in a sheet stream in a sheet transport direction, to front lays of a sheet-processing machine having a lateral pulling device, and a sheet-advancing device disposed within a smallest format width to be processed. The feeding devices includes at least one permanently driven drive roller disposed in the vicinity of the front lays, and at least one contact pressure device cooperatively engageable with the at least one drive roller. The drive roller has a rotational axis directed crosswise to the sheet transport direction, and at least part of the drive roller is disposed laterally of the sheet advancing device.

BACKGROUND OF THE INVENTION 
Field of the Invention 
The invention relates to a device for aligning sheets and, more 
particularly, for feeding sheets with correct registration in sheet-fed 
rotary printing presses. 
It has become known heretofore to provide sheet aligning means, in a 
forward region of feeding tables at sheet-fed rotary printing presses, for 
aligning in lateral and circumferential directions a respective sheet 
conveyed in a sheet stream, before the sheet is transferred to the 
printing press. In this regard, a sheet transported on the feeding table 
by a conveyor device is aligned in the circumferential direction at front 
lays and, thereafter, are drawn up to laterally disposed side stops by 
side pull marks. The problem often arises that the sheet is slightly 
twisted or criss-crossed and no longer rests with correct registration at 
the front lays. 
The published German Patent Document DE 42 41 795 A1, for example, 
discloses a device for feeding sheets to front lays, wherein a cyclically 
driven drive roller cooperates with a counterpart roller. A sheet passed 
between these rollers is thus moved cyclically against front lays both 
before and after the lateral or side alignment has been performed. 
It is disadvantageous that means for cyclic driving have to be provided in 
the device of the foregoing German publication. 
A device has become known heretofore from German Patent 839 644 wherein 
sheets to be aligned are initially transported by means of two parallel 
conveyor belts in a direction towards front lays and, close to the feed 
region, are accepted or taken over by a dabbing device formed of a driven 
lower roller and an upper roller periodically engageable therewith. 
The dabbing device is disposed in an extension of the conveyor belts and 
consequently has the disadvantage that sheets with a format width greater 
than that dictated by the spacing of the conveyor belts are moved away 
from the front lay opposite a respective side pulling device, during a 
lateral alignment by several side pulling devices, so that registration 
problems can arise in the sheet feeder. 
SUMMARY OF THE INVENTION 
It is accordingly an object of the invention to provide a device for 
feeding sheets with correct registration which avoids the foregoing 
disadvantages of the heretofore known devices of this general type. 
With the foregoing and other objects in view, there is provided, in 
accordance with the invention, a device for correctly-registered feeding 
of sheets supplied thereto in a sheet stream in a sheet transport 
direction, to front lays of a sheet-processing machine having a lateral 
pulling device, and a sheet-advancing device disposed within a smallest 
format width to be processed, and comprising at least one permanently 
driven drive roller disposed in the vicinity of the front lays, and at 
least one contact pressure device cooperatively engageable with the at 
least one drive roller, the drive roller having a rotational axis directed 
crosswise to the sheet transport direction, and at least part of the drive 
roller is disposed laterally of the sheet advancing device. 
In accordance with another aspect of the invention, there is provided a 
device for correctly-registered feeding of sheets supplied thereto in a 
sheet stream, to front lays of a sheet-processing machine having a lateral 
pulling device, and a sheet-advancing device disposed within a smallest 
format width to be processed, and comprising permanently driven drive 
rollers disposed in the vicinity of the front lays, and at least one 
contact pressure device cooperatively engageable with each of the drive 
rollers, the drive rollers being disposed in a lateral marginal region of 
the largest format width to be processed and being in continuous operative 
engagement with the respective contact pressure devices. 
In accordance with a further aspect of the invention, there is provided a 
device for correctly-registered feeding of sheets supplied thereto in a 
sheet stream along a sheet travel path, to front lays of a 
sheet-processing machine having a lateral pulling device, and a 
sheet-conveyor device disposed within a smallest format width to be 
processed, and comprising at least one permanently driven drive roller 
disposed in the vicinity of the front lays, at least one contact pressure 
device cooperatively engageable with the drive roller, the drive roller 
extending crosswise to the sheet travel path and being formed as a 
deflecting roller for the sheet-conveyor device laterally of the 
sheet-conveyor belt. 
In accordance with an added aspect of the invention, there is provided a 
device for correctly-registered feeding of sheets supplied thereto in a 
sheet stream in a sheet transport direction, to front lays of a 
sheet-processing machine having a lateral pulling device, and a 
sheet-advancing device disposed within a smallest format width to be 
processed, and comprising at least one permanently driven drive roller 
disposed in the vicinity of the front lays, and at least one contact 
pressure device cooperatively engageable with the at least one drive 
roller, the drive roller being a continuous drive roller disposed 
crosswise to the sheet transport direction, and being disposed in the 
sheet transport direction between the conveyor belt and the front lays. 
In accordance with another feature of the invention, the feeding device 
includes two of the drive rollers, respectively, having has an axial 
length extending crosswise to the sheet transport direction up to the 
sheet advancement devices. 
In accordance with a further feature of the invention, the contact pressure 
device is a freely rotatably supported brush roller. 
In accordance with an added feature of the invention, the feeding device 
includes a crossbar disposed crosswise to the sheet transport direction 
and being in operative engagement with the lateral pulling device. 
In accordance with an additional feature of the invention, the feeding 
device includes lockable slide elements disposed on the crossbar. 
In accordance with yet another feature of the invention, the feeding device 
includes an adjustable spring element connecting the contact pressure 
device to one of the slide elements. 
In accordance with yet a further feature of the invention, the sheet 
advancement device is a conveyor belt having a drive, and the drive roller 
is drivably connected to the conveyor-belt drive. 
In accordance with a concomitant feature of the invention, the sheet 
advancement device is a suction conveyor belt. 
An advantage of the feeding device according to the invention is that even 
during lateral alignment, the permanent transport of the sheet toward the 
front lays is not interrupted. Due to this provision, twisting or canting 
of the sheet during lateral alignment is prevented, or at least continuous 
correction therefore is made. Lengthy pulling paths can thus be traversed, 
even at high printing speeds, without impairing the quality of the 
alignment. 
In particular, an arrangement of additional drive rollers in the marginal 
or border regions of sheets having the largest format width to be 
processed assures a favorable force-application location for advancing the 
sheet to the front lays. 
Another advantage is the saving of space resulting from low structural 
expenditure, which permits the installation of of the feeding device 
according to the invention even in small-format printing presses. 
The displaceability of the contact roller transversely to the sheet 
transport direction makes sensitive adjustment, for example, to print-free 
places, possible. 
An arrangement of contact rollers at the side pull lay, which is movable 
crosswise to the sheet transport direction, permits a simultaneous 
co-adjustment of the contact rollers during a format adjustment. 
An embodiment of the contact roller as a brush roller simplifies a lateral 
motion of the sheet in the side pulling process. 
In a relatively simple manner, the drive for the drive rollers is coupled 
with the drive for the sheet transport on the feeding table. 
In another exemplary embodiment, the deflection rollers for the conveyor 
belt are constructed, respectively, as drive rollers laterally of the 
conveyor belt. This makes for a more compact structure. 
In yet another exemplary embodiment, a continuous drive roller, which is 
disposed crosswise to the sheet transport direction and corresponds to the 
largest format width to be processed, is provided; it is disposed in the 
sheet transport direction between the conveyor belt and the front lays. As 
a Due to this provision, the drive roller can be disposed very close to 
the front lays. 
Other features which are considered as characteristic for the invention are 
set forth in the appended claims. 
Although the invention is illustrated and described herein as embodied in a 
device for aligning sheets, it is nevertheless not intended to be limited 
to the details shown, since various modifications and structural changes 
may be made therein without departing from the spirit of the invention and 
within the scope and range of equivalents of the claims.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the drawings, there is shown therein a feeder table 1 of a 
sheet-fed rotary printing press having spaced-apart front lays 2 and, 
therebetween, pregrippers 5 to which a sheet 3 to be processed is fed for 
alignment in the circumferential direction. The feeding table 1 has at 
least one pulling device 6 in a forward or front region 4 thereof. The 
puller 6 is movable crosswise, i.e., transversely, to the sheet transport 
direction for adjusting the format. A conveyor belt 7 provided in the 
middle of the feeding table 1 is formed with a number of holes 8 which are 
in communication with a non-illustrated suction device. The conveyor belt 
7 extends up close to the front lays 2. Drive rollers 9 are disposed on 
both sides, respectively, of the conveyor belt 7. The drive rollers 9 
extend transversely to the sheet transport direction from a marginal or 
border region of the greatest normal width of the sheet 3 to be processed 
up to the conveyor belt 7. The respective drive rollers 9 are rotatably 
supported or journalled. The disposition of the drive rollers 9 is 
mirror-symmetrically identical, and therefore only the construction of the 
drive roller 9 located on the left-hand side of the conveyor belt 7, as 
viewed in the sheet transport direction, is described hereinbelow. 
As shown in the embodiment of FIG. 2, the drive roller 9 is supported so as 
to be drivable rotatably in bearing blocks below the plane of the table 1 
by two journal pins 11 and 12. The drive roller 9 passes through an 
opening 15 formed in the feeding table 1, so that the outer cylindrical 
surface of the roller 15 is flush with the plane of the table 1 or 
preferably protrudes above it a small distance a equal to approximately 
0.5 to 1 mm. The journal pin 12 carries a pinion 13 which is drivingly 
connected to a drive belt 14. The drive belt 14 is driven by a shaft 16 
which simultaneously serves as the drive means for the conveyor belt 7, so 
that the drive roller 9 and the conveyor belt 7 have the same conveying 
speed. 
The puller 6 is formed, amongst other components, of a pull lay housing 17 
to which a crossbar or traverse 19, which is disposed parallel to the 
drive roller 9, is secured by clamping bolts or mounting studs 18. A 
number of contact pressure elements, such as from one to three thereof, 
which are formed as brush rollers 21, are displaceably disposed on the 
crossbar 19 transversely to the sheet transport direction. The brush 
rollers 21 are freely rotatably mounted at an end of a leaf spring 22. The 
leaf spring 22 is secured to a slide element 23, which is displaceable on 
the crossbar 19 and can be locked by means of a knurled screw 24. 
A second knurled screw 26 is disposed in a continuous threaded bore 27 
formed in the slide element 23 and presses with with an end 28 thereof 
against the leaf spring 22. The adjusting pressure with which the brush 
roller 21 engages the drive roller 9 is finely adjustable by the knurled 
screw 26. By suitably displacing the slide element 23 on the crossbar 19, 
the brush roller 21 is able to be adjusted to engage only print-free areas 
in the subject. 
As shown in the embodiment of FIG. 2, a sheet 3 is transported up to the 
front lays 2 primarily by means of the conveyor belt 7 and, thereat, 
aligned by means of the front lays 2 in the circumferential direction. The 
puller 6 pulls the sheet 3 against the stops provided for lateral 
alignment. Twisting of the sheet 3 is prevented by the fact that the drive 
rollers 9 are permanently driven, even during the lateral alignment, and 
therefore press the sheet 3 constantly against the front lays 2, because a 
fourth engagement location between the drive rollers 9 and the sheet 3 is 
located, in particular, in a lateral marginal or border region of the 
sheet 3. The term "lateral marginal region" is intended to mean the region 
extending up to a side edge of the sheet on either side of the conveyor 
belt 7. 
In the embodiment of FIG. 3, the drive rollers 9 themselves serve as 
deflecting rollers for the conveyor belt 7 and, in the embodiment of FIG. 
4, the drive roller 9 is a continuous drive roller and is disposed between 
the front lays 2 and the conveyor belt 7.