Sheet feeding or delivering – Delivering – With transfer means between conveyor and receiver
Reexamination Certificate
2000-03-29
2001-11-13
Bollinger, David H. (Department: 3651)
Sheet feeding or delivering
Delivering
With transfer means between conveyor and receiver
C271S204000
Reexamination Certificate
active
06315287
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a delivery of a sheet-processing printing machine having grippers which revolve during operation and transfer the processed sheets in a conveying direction to a sheet brake.
The published German Patent Document DE 44 35 988 A1 discloses suction devices revolving at a variable speed, which grip the sheets, respectively, transported via the revolving grippers, in a region of the sheets that is adjacent to the trailing edge, at an instant of time at which the speed of the suction devices coincides with the processing speed of the printing machine. Thereafter, the grippers release the respective sheet gripped by the suction devices and the suction devices are braked to a reduced revolving speed at which they, for their part, finally release the sheets for the purpose of forming a sheet pile.
This process takes place without disruption only when, in particular, assurance is provided that the region of a respective sheet that is to be gripped by the suction devices and is adjacent to the trailing edge of the sheets is guided as far as possible so that it does not flutter about, in particular, at that instant of time at which the suction devices, respectively, are to grip such a region.
Flutter-free guidance of printed sheets in a delivery is also an important precondition for achieving satisfactory printed products with respect to avoiding the smearing or smudging of a printed image applied to the sheets. Efforts to satisfy this precondition can be gathered from the prior art, in particular, from the published German Patent Document DE 42 39 561 A1. This document proposes to avoid whiplash-like movements of the trailing sheet edge by providing a guide surface disposed parallel to the path along which the grippers transport a respective sheet, with positive guidance of the leading edge of the respective sheet, as viewed in the conveying direction, and which can be moved continuously in the conveying direction of the grippers at sheet-conveying speed, the directing surface being formed by a suction-belt arrangement which secures a region of a respective sheet that is adjacent to the trailing edge of the sheet, the region being attached by suction in the process, with the result that a respective sheet is subjected to positive guidance not just in the region of the leading edge thereof, but more-or-less in the region of the trailing edge thereof, as well.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a delivery of a sheet-processing printing machine of the type mentioned in the introduction hereto so as to ensure that the sheets are received reliably by a sheet brake.
With the foregoing and other objects in view, there is provided, in accordance with the invention, a delivery of a sheet-processing printing machine having operationally revolving grippers for transferring processed sheets to a sheet brake in a conveying direction, comprising sheet guides for acting upon lateral borders of the sheets, as viewed in the conveying direction, and for guiding the sheets as they are transferred to the sheet brake.
In accordance with another feature of the invention, the sheet guides are formed with guide surfaces for supporting the lateral borders of the sheets, the lateral borders of the sheets being pressable against the guide surfaces.
In accordance with a further feature of the invention, the delivery has a pressure difference prevailing at the sheets and actionable for pressing the lateral borders of the sheets against the guide surfaces.
In accordance with an added feature of the invention, the delivery includes cyclically operatable hold-downers for pressing the lateral borders of the sheets against the guide surfaces.
In accordance with an additional feature of the invention, the guide surfaces are operationally at a standstill.
In accordance with yet another feature of the invention, the guide surfaces are formed by strands of revolving belts running in the conveying direction during operation.
In accordance with a concomitant feature of the invention, the sheet guides are adaptable to mutual spacing between the lateral borders of the sheets.
Thus, in order to achieve the objective of the invention, sheet guides are provided which act upon the lateral borders of the sheets, as viewed in the conveying direction, and guide the sheets as they are transferred to the sheet brake.
Even at relatively high processing speeds, this achieves largely smooth running of the sheets in a stretch wherein the sheets are to be gripped by the sheet brake. In particular, with the delivery constructed in the foregoing manner, it is possible specifically for a region of a respective sheet which is adjacent to the trailing edge thereof to be gripped reliably by the sheet brake. The delivery is thus suitable, in particular, for braking sheets which are printed on both sides, and thus renders superfluous the operation where the sheet brake is set so that sheets which are printed on both sides thereof are gripped by thereby within non-printed areas running in the conveying direction.
Before the sheet brake is reached, in particular, sheets which are printed on both sides thereof are usually guided, for the purpose of avoiding smearing, over an air cushion formed between the sheet and a sheet-guiding surface, the grippers passing through a gripper path that follows the course of the sheet-guiding surface. In this regard, the air cushion is preferably formed by various arrangements of blast or suction nozzles in the sheet-guiding surface so that smooth running of the sheets over the sheet-guiding surface is achieved. However, in particular, in the region of the sheet brake, the air cushion also forms a flow which, in the case of a conventional delivery, makes it difficult for the respective sheet to be positioned against braking elements of the sheet brake, for example, suction rollers, suction wheels or endless bands or belts passing over a suction box. This disadvantage is also eliminated by the construction of a delivery according to the invention.
An advantageous configuration provides for the sheet guides to be formed with guide surfaces which support the lateral borders of the sheets and against which the lateral borders of the sheets are pressable.
According to a first variation therefrom, the lateral borders of the sheets can be pressed against the guide surfaces preferably under the action of a pressure difference prevailing at the sheets, while, according to a second variation therefrom, the lateral borders of the sheets can be pressed against the guide surfaces by cyclically operated hold-downers. In the case of both variants, according to a first configuration, the guide surfaces preferably remain at a standstill, while, according to a second configuration, they are preferably formed by strands of revolving belts which run in the conveying direction during operation.
Furthermore, for all the variants and configurations, it is preferably provided that the sheet guides be adaptable to the mutual spacing between the lateral borders of the sheets.
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 delivery of a sheet-processing printing machine, 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, wherein:
REFERENCES:
patent: 2924453 (1960-02-01), Peyrebrune
patent: 3941374 (1976-03-01), Vits
patent: 5221079 (1993-06-01), Most et al.
patent: 5431386 (1995-07-01), Blaser
patent: 5582400 (1996-12-01), Seydel
patent:
Hirth Roland
Mack Richard
Bollinger David H.
Greenberg Laurence A.
Heidelberger Druckmaschinen AG
Lerner Herbert L.
Stemer Werner H.
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