Sheet feeding or delivering – Delivering – With transfer means between conveyor and receiver
Reexamination Certificate
2001-03-29
2004-01-27
Walsh, Donald P. (Department: 3653)
Sheet feeding or delivering
Delivering
With transfer means between conveyor and receiver
C271S182000
Reexamination Certificate
active
06682066
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a delivery for a sheet-processing machine, especially a printing machine, including a sheet brake for braking processed sheets from a processing speed to an output speed, a sheet conveyor for transporting the processed sheets in a conveying direction at the processing speed and for transferring the processed sheets to the sheet brake, and structure forming a gap which, during operation, is connected to a vacuum generator and over which the sheet conveyor pulls the sheets for smoothing them before they are transferred to the sheet brake, and also to a sheet-processing machine, especially a printing machine, equipped with the delivery.
A delivery of the foregoing type is disclosed in published Swiss Patent Document CH 611 579 A5 which describes a subassembly by which, directly after the processed sheets have been smoothed out, the sheets are braked. This subassembly is formed with two gaps following one another in the processing direction and, during operation, connected to a vacuum generator. A sheet conveyor having grippers which grip a respectively leading edge of the sheets guides the sheets over the two gaps. In order to smooth the sheets out, provision is made for them to be pulled into that gap which is upline of the other of the two gaps, under the action of the vacuum generator, as the sheets sweep over the subassembly, while a respective leading edge of the sheets is positively guided by the grippers. The positive guidance of a respective one of the sheets is discontinued when the sheet leaves the upline gap but still covers the downline gap of the two gaps. With this deliberate discontinuance or cancellation of the positive guidance of the respective sheet, provision is made for braking the latter under the action of the vacuum generator by sucking the sheet against the edges of the downline gap.
This braking process is difficult to control, however, particularly inasmuch as when the respective sheet exposes the upline gap, the pressure relationships in this gap and in the downline gap are changed abruptly.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a delivery of a sheet-processing machine of the foregoing general type with a subassembly which permits the smoothing and subsequent braking of a respective sheet and which, when the braking process is started, does not cause any change in the pressure relationships created by the vacuum generator. With the foregoing and other objects in view, there is provided, in accordance with one aspect of the invention, a delivery for a sheet-processing machine, comprising a sheet brake for braking processed sheets from a processing speed to an output speed, a sheet conveyor for transporting the processed sheets in a conveying direction at the processing speed and for transferring the processed sheets to the sheet brake, and a body defining a gap which, during operation, is connected to a vacuum generator and over which the sheets are pullable by the sheet conveyor for smoothing the sheets before they are transferred to the sheet brake, the gap being formed at the sheet brake.
In accordance with another feature of the invention, the sheet brake includes a rotating body having a cylindrical outer face which, during operation, rotates positively at a peripheral speed lower than the processing speed, forms with the outer face thereof a first edge of the gap, which is at a downline location with respect to the conveying direction, and pulls a respective sheet, which is transferred to the sheet brake and braked, over the gap in the conveying direction.
In accordance with a further feature of the invention, a second edge defining the gap is formed on a component that is stationary during operation, the second edge being upline from the first edge with respect to the conveying direction.
In accordance with an added feature of the invention, the delivery includes a further cylindrical rotating body which, with a cylindrical outer face thereof, forms a second edge of the gap, the second edge being disposed upline from the first edge with respect to the conveying direction, the two rotating bodies having identical rotational movements during operation.
In accordance with an additional feature of the invention, the cylindrical rotating body forming the first edge is formed as a hollow body with an outer jacket having apertures formed therein and communicating with the interior of the hollow body.
In accordance with another aspect of the invention, there is provided a sheet-processing machine, including a delivery, comprising a sheet brake for braking processed sheets from a processing speed to an output speed, a sheet conveyor for transporting the processed sheets in a conveying direction at the processing speed and for transferring the processed sheets to the sheet brake, and a body defining a gap which, during operation, is connected to a vacuum generator and over which the sheets are pullable by the sheet conveyor for smoothing the sheets before they are transferred to the sheet brake, the gap being formed at the sheet brake.
In accordance with a concomitant aspect of the invention, there is provided a printing machine, including a delivery, comprising a sheet brake for braking processed sheets from a processing speed to an output speed, a sheet conveyor for transporting the processed sheets in a conveying direction at the processing speed and for transferring the processed sheets to the sheet brake, and a body defining a gap which, during operation, is connected to a vacuum generator and over which the sheets are pullable by the sheet conveyor for smoothing the sheets before they are transferred to the sheet brake, the gap being formed at the sheet brake.
Thus, in order to achieve the objective of the invention, the gap provided in the delivery described in the introduction hereto for smoothing a respective sheet is formed at the sheet brake. To this extent, this gap is given a dual function, because, under the action of the vacuum generator, it smoothes the respective sheet positively guided by the sheet conveyor by pulling the sheet into the gap and, after the sheet has been released by the sheet conveyor, the gap continues to remain as a vacuum chamber that is covered by the respective sheet, with the effect that the released sheet is pressed against the edges defining the gap by a vacuum prevailing in the gap and, in the process, is braked.
Furthermore, this dual function also leads to this extent to a simpler construction of the subassembly serving to smooth and brake the sheets, than that required by just a single gap for smoothing and braking.
According to a development, provision is made for the sheet brake to comprise a rotating body having a cylindrical outer face which, during operation, rotates positively at a peripheral speed lower than the processing speed, forms with the outer face a first edge of the gap, which is downline with respect to the conveying direction, and pulls a respective sheet, which is transferred to the sheet brake and braked, over the gap in the conveying direction.
Assurance is therefore provided that a respective sheet is not braked to a standstill before it has left the sheet brake.
The reason for this is that, in the aforementioned development, the rotating body forming the first edge of the gap exerts a forward drive force directed in the processing direction on the braked sheet, in spite of the braking action of the sheet brake.
Although, in the aforementioned development, the sheet brake has a braking element in the form of the rotating body forming the first edge, it has a greater braking action than a conventional sheet brake, disclosed for example by the published German Patent Document DE 196 16 423 C2, having a braking element formed as a rotating body, in the outer cylindrical face of which there terminate suction openings which, during operation, successively communicate with a vacuum generator and through which, in particular in the case of relatively stiff sheets, a given amount
Gunschera Frank
Kerpe Sven
Greenberg Laurence A.
Heidelberger Druckmaschinen AG
Locher Ralph E.
Miller Jonathan R.
Stemer Werner H.
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