Method and delivery for a sheet-processing machine

Abstract

A method of depositing sheets coming out of a sheet-processing machine includes decelerating the sheets and depositing the sheets of a main pile. Certain sheets are decelerated and fed to a second sheet pile. The system includes a device for decelerating the sheets arriving from the sheet-processing machine and for depositing the sheets on a main pile. A chain gripper system is configured to hold and decelerate a trailing edge of the sheets. The chain gripper system includes an adjustable gripper opening cam.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a diagrammatic sectional view of a sheet-fed rotary printing press;

FIG. 2 is a diagrammatic side view of the delivery according to the invention; and

FIG. 3 is a diagrammatic plan view of the path of sheet travel in the delivery.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the figures of the drawing in detail and first, particularly, to FIG. 1 thereof, the sheet-processing machine according to the invention may be, for example, a sheet-fed rotary printing press 1. The press 1 comprises a feeder 2 and at least one printing unit 3, 4. A delivery 6 follows the last printing unit. Sheets 7 are separated from a sheet pile 8, moved over a feed table 9, and fed to the printing units 3 and 4 either individually or in a shingled, imbricate stream. As it is known in the art, each of the printing units 3 and 4 includes a plate cylinder 11 and 12, respectively. Each of the plate cylinders 11 and 12 includes a device 13, 14 for locking flexible printing plates. In addition, a device 16, 17 for performing semi-automatic or automatic plate changes is associated with each of the plate cylinders 11, 12. A three-drum reversing device 27, 28, 29 is provided between the impression cylinders 25, 30 of the printing units 3, 4. The reversing device, which is of conventional construction, includes a transfer drum 27, a storage drum 28, and a reversing drum 29.

The sheet pile 8 rests on a pile plate 10, which can be lifted in a controlled manner. The sheets 7 are drawn from the upper side of the sheet pile 8 by means of a so-called suction head 18, which includes, among other features, a number of lifting and dragging suction cups 19, 21 for separating the sheets 7. In addition, the feeder comprises blower devices 22 for loosening the upper sheets and sensing devices 23 for causing the sheet pile 8 to be lifted. To align the sheet pile 8, in particular the upper sheets 7 in the pile 8, a number of lateral and rear stops 24 are provided.

The delivery 6 is designed as a chain delivery. Two parallel chains 33, which revolve endlessly about sprockets 31, 32, carry gripper bars 34 for holding the leading edges of the sheets and gripper bars 36 for holding the trailing edges of the sheets. A sheet braking or sheet deceleration system, for example in the form of another chain gripper system 38, is provided upstream of a sheet delivery pile. The chain gripper system 38 carries a gripper bar 39 for holding the trailing edge of the sheets. It is driven in accordance with the machine cycle of the sheet-processing machine and decelerates the sheet to be deposited from a print-run speed to a predetermined depositing speed. An adjustable gripper opening cam 41 opens the grippers of the gripper bar 39 to release the trailing edge of the sheets.

A “vision control” sheet inspection device 42 is preferably provided in the region of the last impression cylinder 30. The sheet inspection device 42 is equipped with an ink density and register detection sensor. It forwards measured values to a control computer 43. The control computer 43 carries out a comparison between measured values and desired values. If a deviation is detected, the gripper opening cam 41 is displaced. As a consequence, the sheet, which is held at the trailing edge by the gripper bar 39, is not released, but is dragged through a short distance s against the main depositing direction.

In a position B, which is spaced from a position A by the spacing distance s, the grippers of gripper bar 39 open and release the sheet. This causes the trailing edge of the sheet to be deposited on a conveying device 44. Conveying device 44 preferably consists of a suction belt that is driven in a pulsed manner and feeds the sheet to an auxiliary or waste sheet pile 46 at a depositing speed, which is lower than the print-run speed. Blower devices 45 are provided above the waste sheet pile 46 to assist the deposition of the sheets.

A blower bar 47 with a number of blower nozzles 48 is arranged above the main pile 37 to generate an air cushion above the main pile 37 by means of a stream of blast air directed parallel to the upper side of the main pile 37. This air cushion is activated whenever a sheet is to be deposited on the waste sheet pile 46 so that the sheet can be drawn off the main pile on the air cushion without contacting the main pile.

Claims

1. A method of depositing sheets arriving from a sheet-processing machine, which comprises: decelerating the sheets and depositing the sheets on a main delivery pile; andselectively feeding selected, decelerated sheets to a second sheet pile.

2. The method according to claim 1, which comprises inspecting the sheets and determining which sheets are to be fed to the second sheet pile based on the inspection and a comparison between measured values and desired values.

3. A device for depositing sheets arriving from a sheet-processing machine, comprising: a device for decelerating the sheets arriving from the sheet-processing machine and for depositing the sheets on a main pile;a chain gripper system configured for holding and decelerating a trailing edge of a respective sheet, said chain gripper system including an adjustable gripper opening cam.

4. The device according to claim 3, wherein said chain gripper system is configured such that, upon adjustment of said adjustable gripper opening cam, a certain sheet is conveyed to a waste sheet pile.

5. The device according to claim 4, wherein a conveying direction of the sheet towards the waste sheet pile is opposite a conveying direction of the sheets towards the main pile.

6. The device according to claim 5, which comprises a blower bar disposed above the main pile.

7. The device according to claim 6, comprising blast-air nozzles disposed at said blower bar and oriented to blow air in a horizontal direction.

8. The device according to claim 3, which comprises a sheet inspection system disposed to inspect and measure the sheets in-line.

9. The device according to claim 8, wherein said sheet inspection system acquires and transmits measured values to a control computer, and said control computer is configured to control said adjustable gripper opening cam in dependence on a comparison between measured values acquired by said sheet inspection system and desired values.

10. The device according to claim 4, comprising a conveying belt disposed between the main pile and the waste sheet pile for transporting and decelerating the certain sheet.

11. The device according to claim 10, wherein said conveying belt is a suction belt.

12. A sheet-fed printing press comprising the device according to claim 3 disposed in a delivery of the sheet-fed printing press.