Patent Application
20100072695
This application claims the priority, under 35 U.S.C. §119, of German Patent Application DE 10 2008 048 407.5, filed Sep. 23, 2008; the prior application is herewith incorporated by reference in its entirety.
The invention relates to a method and a device for ejecting defective sheets at a feeder of a processing machine, in particular a sheet-fed rotary printing machine. The invention also relates to a feeder in a sheet-fed rotary printing machine having the ejecting device.
The detection of defective sheets at the feeder of a processing machine gives rise to the problem that the machine has to be stopped in order for a sheet identified as a defective sheet not to be conveyed into the machine. An appropriate method is disclosed in German Published, Non-Prosecuted Patent Application DE 101 05 991 A1.
A device for ejecting a sheet at the delivery is described, for example, by German Published, Non-Prosecuted Patent Application DE 10 2005 004 881A1. In that case, a deflecting device is pivoted into an interspace between two grippers of a sheet-transporting chain-gripper system.
It is accordingly an object of the invention to provide a method and a device for ejecting defective sheets and a feeder having the ejecting device, which overcome the hereinafore-mentioned disadvantages of the heretofore-known methods and devices of this general type and which can be used at a feeder of a processing machine.
With the foregoing and other objects in view there is provided, in accordance with the invention, a method for ejecting a defective sheet. The method comprises providing a processing machine with a feeder at which the defective sheet is to be ejected, a sensor for sensing defective sheets, a cylinder, gripper devices, and a transporting station for feeding a sheet to the cylinder. A sheet identified as a defective sheet is transported through the transporting station with deceleration and the sheet is transported further without the defective sheet being received by the gripper devices.
With the objects of the invention in view, there is also provided, in a processing machine having a feeder, a cylinder and a machine drive, a device for ejecting a defective sheet at the feeder. The device comprises a transporting station for feeding sheets to the cylinder. The transporting station has a drive to be regulated in time, cycle or sequence with the processing machine, but independently of the machine drive.
In accordance with another particularly advantageous feature of the invention, the sheets identified as defective sheets are not fed to the processing machine and stoppage of the processing machine is avoided at the same time. In a particularly advantageous manner, it is provided that blanket cylinders disposed in the printing units are disconnected one after the other from the impression cylinder in accordance with the arrival of the ejected defective sheet.
In accordance with a further feature of the invention, the transporting device for feeding the sheets to the feed cylinder is advantageously constructed as a suction belt. As a result of this measure, the transporting device also serves for transporting the sheet during the ejecting operation. The ejecting device is formed by a curved directing plate on which the defective sheet is guided to a depositing location in part by the motive power of the suction belt and in part by the gravitational force acting on the sheet.
In accordance with a concomitant advantageous feature of the invention, transporting rollers, which can be driven in opposite directions, grip the sheet securely and transport it away to be disposed in an ejecting path.
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 method and a device for ejecting defective sheets at a feeder of a processing machine and a feeder having the ejecting device, 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 stacking panel 10 which can be raised in a controlled manner. 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 has, inter alia, a number of lifting and pulling suckers 19, 21 for separating the sheets 7. Also provided are blowing devices 22 for loosening the top sheet layers and follower elements 23 for stack adjustment. A number of lateral and rear stops 24 are provided in order to align the sheet stack 8, in particular the top sheets 7 of the sheet stack 8.
The sheet-feeding device 27 is constructed as a second transporting station disposed downstream of the feed table 9, which is constructed as a so-called “suction-belt table,” as seen in a sheet-transporting direction. This second transporting station 27 accelerates the sheet 7 before the latter is gripped by a gripper device 28 of a cylinder 26, e.g. a feed cylinder. The transporting station 27 may, for example, be a pre-gripper or a gripper device which is driven in linear fashion.
In the exemplary embodiment according to
During routine operation of the machine, the respectively front sheet 7 of a sheet stream conveyed over the feed table 9 is gripped by the transporting station 27 and accelerated to machine speed or the speed of the feed cylinder 26. The gripper device 28 of the feed cylinder 26 grips the sheet 7 at its leading edge and transports it to a downstream cylinder 37, e.g. to an impression cylinder of the printing machine 1.
Beneath the feed cylinder 26, but above a feed plane E formed by the feed table 9 and the second transporting station 27, a preferably stationary directing device 38, e.g. a curved directing plate, of an ejecting device, is provided downstream of the location at which the leading sheet edge is transferred to the gripper device 28. This directing plate intersects the plane E and forms a guide for an ejected sheet 7a, with the guide terminating in a depositing location 39.
In the case of the exemplary embodiment according to
When a defective sheet 7a is sensed by the sensor 34, the control computer 26 generates a signal which causes the transporting station 27 to accelerate the sheet 7a, or if necessary to brake it, only to the extent where, rather than it being gripped cyclically by the gripper device 28, it is transported further through the transporting station 27 on the plane E. In the case of the preferred exemplary embodiment according to
A further method step involves blanket cylinders being disengaged from their respective impression cylinders at a point in time at which the defective sheet 7a would have passed through the respective nip between the blanket cylinder and impression cylinder, in order to ensure that the application of ink on the blanket cylinder which was intended for the sheet 7a does not soil the impression cylinder.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2008 048 407.5 | Sep 2008 | DE | national |
