Patent Application
20090250869
1. Field of the Invention
The invention relates to an apparatus for aligning sheets through the use of stops disposed on a cylinder of a sheet-processing machine, in particular so-called front lays.
European Patent EP 0 120 348 B1, corresponding to U.S. Pat. No. 4,588,184, discloses providing an alignment cylinder with front lays for reliable front edge alignment during continuous sheet feeding. The front lay stops are firmly connected to the alignment cylinder so as to rotate with it in a row transverse to the sheet transport direction. The front lay stops describe a circular path during the rotation of the alignment cylinder as a result of their configuration on the circumference of the alignment cylinder.
It is accordingly an object of the invention to provide an apparatus for aligning sheets through the use of stops disposed on a cylinder, which overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type and which provides an alternative apparatus for the alignment of a sheet moving in the sheet transport direction.
With the foregoing and other objects in view there is provided, in accordance with the invention, a sheet aligning apparatus disposed at an end of a feed table in a sheet processing machine, in particular a printing press. The apparatus comprises an alignment cylinder, stops disposed on the alignment cylinder for sheets conveyed to the stops at a predefined speed, and at least one cam mechanism for producing a translational movement of the stops.
It is a particular advantage of the invention that the front lays execute a translational movement during the alignment process. As a result of this measure, relative movement between the front edge of the sheet and the front lays is avoided.
In an advantageous refinement, a cam mechanism is provided which superimposes a second movement component on the rotational movement of the front lay, so that a translational direction of movement of the front lays is produced. The cam mechanism interacts with a stationary control cam.
Other features which are considered as characteristic for the invention are set forth in the appended claims and further advantageous refinements can be gathered from the subclaims.
Although the invention is illustrated and described herein as embodied in an apparatus for aligning sheets through the use of stops disposed on a cylinder, 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.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
Referring now to the figures of the drawings in detail and first, particularly, to
The sheet stack 8 rests on a stack board 10 which can be raised under control. The sheets 7 are removed from the top side of the sheet stack 8 through the use of a so-called suction head 18 which, inter alia, has a number of lifting and dragging suckers 19, 21 to separate the sheets 7. Furthermore, blowing devices 22 are provided to loosen the upper sheet layers, and sensing elements 23 for stack tracking. A number of side and rear stops 24 are provided in order to align the sheet stack 8, in particular the upper sheets 7 of the sheet stack 8.
At the end of the feed table 9 which, in particular, is a suction conveyor belt table, there is disposed a printing unit cylinder, e.g. a feed cylinder 26, which grips the sheets 7 at their front edge and transfers them to a downstream cylinder 27, for example an impression or printing cylinder.
As is best seen in
In order to align a front edge of a sheet, the front lay stops 31 are pivoted out of the periphery of the alignment cylinder 28 as far as the plane E. The sheet 7 is conveyed against the front lay stops 31 through the use of transport systems disposed on the feed table 9, for example a suction belt, at a speed V1 which is higher than a speed V2 of the front lay stops 31 in the sheet transport direction. In this case, the sheet 7 is aligned in the sheet transport direction and with respect to a skewed position.
Following completion of an alignment phase, the sheet is picked up by transport grippers 39 of the feed cylinder 26. A speed V3 of the transport grippers 39 is then synchronized with the speed V2 of the stops, which means that the speed V2=V3 during the closure of the grippers 39.
During the alignment phase, the front lay stops 31 are moved translationally along an imaginary extension—plane E—of the feed table 9. During the alignment phase, the sheet is aligned in the sheet transport direction and with respect to a skewed position on the front lay stops 31 and is then gripped by the transport grippers 39 of the feed cylinder 26. After the closure of the transport grippers 39, the front lay stops 31 dip into the periphery of the alignment cylinder 28 until, shortly before reaching the plane E, they are pivoted out of the periphery of the alignment cylinder 28 again as far as the plane E for the alignment of the next sheet 7.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2008 014 592.0 | Mar 2008 | DE | national |
This application claims the priority, under 35 U.S.C. § 119, of German Patent Application DE 10 2008 014 592.0, filed Mar. 17, 2008; the prior application is herewith incorporated by reference in its entirety.
