Sheet feeding or delivering – Feeding – Separator and conveyor
Patent
1992-09-02
1994-05-03
Dayoan, D. Glenn
Sheet feeding or delivering
Feeding
Separator and conveyor
271 11, 271105, 271107, 271226, B65H 508
Patent
active
053080556
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a tractor nozzle device for fast running sheet feeders. The sequential feeding of individual sheets of a sheet stack to a printing press, such as an offset printing press, is performed so that the sheets are brought into a scale-like arrangement. This scale-like alignment of the sheets lifted off a sheet stack and appropriately pushed forward is performed with so-called suction heads.
To form this scale-like arrangement in the running direction of the sheet feeder, the tractor nozzles are required to make a back-and-forth or oscillating movement. In addition, the tractor nozzles must be able to perform a deflection movement, because the stacks or the individual sheets of such stacks are not exactly aligned in the feed direction of a printing press. It is therefore necessary that the suction heads also have a so-called correction feature for slanted sheets.
DESCRIPTION OF THE PRIOR ART
A known tractor nozzle device of the type mentioned above has a rocker which can perform an oscillating back-and-forth movement. This oscillating movement is generated by means of a cam roller fixed on the rocker and connected fixed against tension and pressure to a cam plate. At the lower stop of the rocker, an approximately horizontally oriented support bridge is provided which, together with the rocker, performs the approximately horizontally oscillating movement. At the back this support bridge is seated supported by means of rollers in such a way that during its back-and-forth movement it is also seated supported at its back end. These rollers can additionally be deflected sideways, so that the support bridge can also perform a laterally deflected movement. In case of a not quite exact positioning of the sheets, this lateral deflection movement provides the required correction of slanted sheets. The front end of this support bridge is rotatably connected with the rocker via a first bearing in order to make the back-and-forth movement of the support bridge together with the rocker possible in this way. The front end of the support bridge is additionally fastened on the rocker via a second bearing, which allows the required lateral deflection movement of the support bridge.
So-called sliding or rolling bearings are used for embodying these bearings. Because of the quite high clock rate of sheet feeders, which may be around 12,000 back-and-forth movements per hour in known sheet feeders, the direction of rotation of these rolling bearings must be reversed correspondingly often. These very fast changes in the direction of rotation cause high acceleration forces on the rotating parts in the bearing and worsen the lubricant supply to the inside of the bearing, so that these bearings tend to pit. Because of the design of the bearing between the rocker and the support bridge in the form of two independent bearings, this junction has a relatively large inherent weight, so that correspondingly high oscillations and great wear is to be expected. Thus clock rates above 15,000 back-and-forth movements per hour are not possible. Because of component-related tolerances between the bearing and the rocker or support bridge, after a while the pressure forces of the rollers against the roll-off faces of the slant adjustment are no longer sufficient on account of the slippage caused by the reversal of the direction of running or rotation, which additionally results in rapid wear.
SUMMARY OF THE INVENTION
Based on this state of the art, it is the object of the invention to provide a tractor nozzle device for fast running sheet feeders which does not have the disadvantages known from the prior art and which therefore makes long service life and as high a possible clock rates possible.
The previously mentioned tractor nozzle device known from the prior art is therefore distinguished in that rubber-metal elements, in particular rubber-metal bushings are provided as bearings for the mutual absorption of the back-and-forth movements as well as the additional deflection movements. Such bushing
REFERENCES:
patent: 2238435 (1941-04-01), Perry
patent: 2251416 (1941-08-01), Parker
patent: 2722416 (1955-11-01), Backhouse
patent: 2772104 (1956-11-01), Thiry
patent: 3893775 (1975-07-01), Sievers et al.
patent: 4671678 (1987-06-01), Munch
patent: 4786043 (1988-11-01), Jiruse et al.
Machine Design, vol. 44, No. 29; Nov. 30, 1972; pp. 56-61; "Rubber Bearings"; Eugene Sprow.
Russian text; p. 523; published 1988.
Dayoan D. Glenn
Koenig & Bauer Aktiengesellschaft
Milef Boris
LandOfFree
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