Device and Method for Driving a Reversing Gripper in a Sheet-Processing Machine, Reversing Drum and Printing Press

Abstract

A reversing gripper system of a sheet-processing machine includes respective drive motors for driving cooperating fixed grippers and spring-loaded grippers to create pivoting and opening movements. The motors may be stationary or may be disposed inside the periphery of a reversing drum. A transmission between a drive motor and the gripper system preferably includes a belt drive. A reversing drum, a printing press and a method of automated electronic adjustment of a gripper position and of gripper opening and closing times, are also provided.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

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

FIG. 2 is an enlarged, fragmentary, partly broken-away and partly sectional, front-elevational view of a gripper system driven by stationary drive motors;

FIG. 3 is a view similar to FIG. 2, showing the gripper system driven by drive motors disposed on a reversing drum; and

FIG. 4 is a cross-sectional view of the gripper system with stationary drive motors.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the figures of the drawings in detail and first, particularly, to FIG. 1 thereof, there is seen a machine for processing sheets 7, for example a printing press 1, which includes a feeder 2, at least one printing unit 3, 4 and a delivery 6. The sheets 7 are taken from a sheet pile 8 and are fed to the printing units 3 and 4 over a feed table 9 as individual sheets or in a shingled stream. Each of the printing units 3, 4 includes a plate cylinder 11, 12, as is known in the art. Each of the plate cylinders 11 and 12 includes a device for fixing flexible printing plates. In addition, a device 16, 17 for semi-automatic or fully automatic plate changing is associated with each of the cylinders 11, 12.

The sheet pile 8 rests on a pile plate 10 that can be lifted in a controlled manner. The sheets 7 are removed from the top of the sheet pile 8 through the use of what is referred to as a suction head 18 which includes, among other elements, a number of lifting and dragging suckers 19, 21 for separating the sheets 7. Moreover, blower devices 22 for loosening the upper layers of sheets are provided as well as sensing elements 23 for initiating the lifting of the sheet pile. A number of lateral and trailing-edge stops 24 is provided to align the sheet pile 8, in particular the upper sheets 7, in the pile 8.

A three-drum reversing device 26 is provided between two impression cylinders 31 and 40. The three-drum reversing device 26 is formed of a transfer drum 27, a storage drum 28 and a reversing drum 29. The reversing drum 29 includes a pincer gripper system 32 for reversing the sheets in a perfecting mode, i.e. in a printing mode in which both sides of the sheets are printed in one pass as opposed to a straight-printing mode in which only one side of the sheets is being printed. Each of the remaining sheet-guiding cylinders includes gripper systems for transporting the sheets. As is seen in FIGS. 2, 3 and 4, the pincer or pliers-type gripper system 32 is formed of at least one fixed or rigid gripper 33, which forms a gripper pad, and a spring-loaded or spring-mounted gripper 34, which forms a gripper finger. In the perfecting mode, the grippers 33 and 34 are capable of being pivoted about a common axis 36. The grippers 33 are disposed on a gripper shaft 37 that is coaxially surrounded by a gripper tube 38. The grippers 34 are disposed on the gripper tube 38. The entire gripper system 32 is supported on the reversing drum 29 so as to be capable of being pivoted.

As is seen in FIG. 2, a pulley 41 is located on a first end of the gripper shaft 37. The pulley 41 is in drive connection with a pulley 43 through the use of a driving belt 42, preferably a toothed belt or timing belt. A gearwheel 44, that is driven by a pinion 46 of a stationary drive motor 47, is disposed parallel to the pulley 43.

The pulley 43 and the gearwheel 44 are jointly supported on a journal 48 of the reversing drum 29, so as to be capable of rotating.

A pulley 51 is located on a first end of the gripper tube 38. The pulley 51 is in drive connection with a pulley 53 through the use of a driving belt 52, preferably a toothed belt or timing belt. A gearwheel 54, which is driven by a pinion 56 of a stationary drive motor 57, is disposed parallel to the pulley 53. The pulley 53 and the gearwheel 54 are jointly supported on a journal 55 of the reversing drum 29.

The drive motors 47, 57 are driven in dependence on the speed of the reversing drum or the speed of the machine. In order to create a pivoting movement, i.e. a joint movement of the fixed gripper 33 and the spring-loaded gripper 34, the drive motors 47, 57 are driven in synchronism at a speed that is higher or lower than the speed of the reversing drum.

In order to create an opening or closing movement of the fixed gripper 33 and the spring-loaded gripper 34, the drive motor 57 is driven at a higher or lower speed than the reversing drum 29, while the drive motor 47 is driven at the same speed as the reversing drum 29.

In a second exemplary embodiment, which is shown in FIG. 3, the drive motors 47, 57 are disposed on or in the reversing drum 29. In this case, they operate as simple servomotors, because they rotate together with the drum.

The drive motors 47, 57 are, for example, disposed inside the periphery of the reversing drum 29. Each of the drive motors 47, 57 includes a respective drive shaft 61, 62. Each of the drive shafts 61, 62 supports a respective pulley 63, 64 and a respective incremental disc 66, 67. The incremental disc 66 cooperates with a sensor 68 that is connected to a machine control unit 69. The incremental disc 67 cooperates with a sensor 71, which is likewise connected to the machine control unit 69.

The pulley 63 drives the gripper shaft 37 through the use of a timing belt 72 and a pulley 73. The pulley 73 is disposed approximately at the center of the gripper shaft 37.

The pulley 64 drives the gripper tube 38 through the use of a timing belt 74 and a pulley 76. The pulley 74 is likewise disposed approximately at the center of the gripper tube 38.

The drives 47, 57 are connected to the machine control unit 69, in which predetermined paths of movement and opening times for the gripper system 32 are stored, for the control (open-loop control) or regulating (closed-loop control) of the drives 47, 57. The sensor 68 indirectly detects the gripper position (gripper height) of the fixed gripper 33 in cooperation with the incremental disc 66. Alternatively, it is possible to directly detect the gripper position of the fixed gripper 33 through the use of a sensor 70.

The sensor 71 indirectly detects the gripper position of the spring-loaded gripper 34, in cooperation with the incremental disc 67.

Both of the motors 47 and 57 are position-controlled through the use of the machine control unit or computer 69. In addition, the motor 57 is force-controlled for the purpose of generating the appropriate predetermined holding forces.

The motors 47, 57 drive the grippers 33, 34 under the control of the machine control unit or computer 69 as defined by the respective predetermined path of movement for a selected mode of operation. In addition, optimized regulating (closed-loop control) takes place due to the data provided by the sensors. Both grippers 33, 34 are initially regulated (closed-loop control) in position. In the closing point, the gripper 33, which forms the gripper pad, is held in its position (height), while the gripper 34, which carries out the closing movement, pivots under force control until the required holding force is reached. The holding force may be predetermined depending on the subject to be processed or may be determined automatically.

A user interface of the machine control unit or computer 69 is used to select a different mode of operation, for example the perfecting mode. The motors 47, 57 are then controlled in a way that corresponds to the path of movement that is predetermined for this mode of operation. For the regulating (closed-loop control) through the sensors 68, 71, the computer prescribes new desired values in a corresponding way. No mechanical adjustments are required for this purpose.

The grippers 33, 34 are moved to their desired positions by motors for the electronic adjustment of the gripper control times at reference machine positions (gripper opening, gripper closing, transfer center). In a regulating (closed-loop control) operation, the actual position is corrected, and the association of gripper position and incremental encoder of the motor are stored. Due to such a correction of the actual position, a basic adjustment between motor 47, 57 and gripper 33, 34 for the predetermined path of movement is achieved. If required, the machine may automatically repeat such a calibration process at certain intervals, for example to compensate for a mispositioning of the grippers 33, 34 due to wear.

An additional recommendation is to provide collision protection for security purposes to prevent the gripper systems from pivoting or opening in the case of a failure of the servomotors or drive.

Claims

1. A device for pivoting and opening a pincer gripper system of a sheet-transporting drum, the pincer gripper system formed of a number of fixed grippers and a number of spring-loaded grippers cooperating with the fixed grippers, the device comprising: a first drive motor for driving the fixed grippers; anda second drive motor for driving the spring-loaded grippers;said drive motors being controlled or regulated in mutual dependence on each other.

2. The device according to claim 1, wherein said drive motors are stationary, and said drive motors are each in drive connection with the gripper system through a respective transmission.

3. The device according to claim 1, wherein said drive motors are disposed inside a periphery of the sheet-transporting drum, and said drive motors are each in drive connection with the gripper system through a respective transmission.

4. The device according to claim 2, wherein said transmissions each include a belt drive.

5. The device according to claim 3, wherein said transmissions each include a belt drive.

6. The device according to claim 3, which further comprises a machine control unit driving said first drive motor in a position-controlled manner and driving said second drive motor in a position-controlled and a force-controlled manner.

7. The device according to claim 4, wherein said drive motors have incremental encoders, and sensors each determine a position of a respective one of said drive motors and cooperate with a respective one of said incremental encoders.

8. The device according to claim 5, wherein said drive motors have incremental encoders, and sensors each determine a position of a respective one of said drive motors and cooperate with a respective one of said incremental encoders.

9. A reversing drum, comprising a pincer gripper system, and a drive for said pincer gripper system according to claim 1.

10. A sheet-fed rotary printing press, comprising a reversing drum having a pincer gripper system, and a drive for said pincer gripper system according to claim 1.

11. A method of automated electronic adjustment of a gripper position and of gripper opening and closing times, the method comprising the following steps: determining actual positions of fixed and spring-loaded grippers in a desired position; andthen controlling motors driving the grippers until the grippers reach the desired position.