Printing unit wrapping strips of tobacco and a printing method

Abstract

A printing unit for applying print marks to a wrapping strip in a cigarette rope machine of the tobacco processing industry is provided. The printing unit includes at least one printing cylinder, a counter-pressure cylinder in contact with the at least one printing cylinder, and a fastening device adapted to jointly attach and detach the at least one printing cylinder and the counter-pressure cylinder to the cigarette rope machine.

1 - 23 . (canceled).  
     
     
         24 . A printing unit for applying print marks to a wrapping strip in a cigarette rope machine of the tobacco processing industry, said unit comprising: 
 at least one printing cylinder;    a counter-pressure cylinder in contact with the at least one printing cylinder; and    a fastening device adapted to jointly attach and detach the at least one printing cylinder and the counter-pressure cylinder to the cigarette rope machine.    
     
     
         25 . The printing unit according to  claim 24 , further comprising a bearing support, wherein the at least one printing cylinder and the counter-pressure cylinder are mounted on the bearing support such that the fastening unit attaches and detaches the unit to and from the machine as a single unit.  
     
     
         26 . The printing unit according to  claim 25 , wherein the bearing support includes two bearing plates between which the at least one printing cylinder is arranged.  
     
     
         27 . The printing unit according to  claim 24 , further comprising a spindle, wherein the counter-pressure cylinder is positioned so as to rotate freely on the spindle, and wherein the at least one printing cylinder is adapted to be driven by at least one electric motor.  
     
     
         28 . The printing unit according to  claim 25 , wherein the fastening device is connected to the bearing support.  
     
     
         29 . The printing unit according to  claim 28 , wherein the fastening device includes a bolt that supports the bearing support, and wherein the bolt has one end to be screwed into a machine wall of the machine.  
     
     
         30 . The printing unit according to  claim 29 , further comprising a lever at the other end of the bolt for detaching or fastening the bearing support.  
     
     
         31 . The printing unit according to  claim 29 , wherein the bearing plates have bores through which the bolt extends.  
     
     
         32 . The printing unit according to  claim 27 , further comprising a position-specified coupling provided between the at least one electric motor and the at least one printing cylinder such that, upon installation of the printing unit, the at least one printing cylinder assumes a predetermined angle of rotation position within the cigarette rope machine.  
     
     
         33 . The printing unit according to  claim 24 , further comprising an adjustment device for positioning the counter-pressure cylinder relative to the at least one printing cylinder.  
     
     
         34 . The printing unit according to  claim 33 , wherein the adjustment device includes at least one screw bolt.  
     
     
         35 . The printing unit according to  claim 33 , further comprising an elastic, resilient bearing element for the spindle of counter-pressure cylinder to allow for an adjustment movement.  
     
     
         36 . The printing unit according to  claim 24 , wherein the at least one printing cylinder includes at least two printing cylinders.  
     
     
         37 . The printing unit according to  claim 27 , further comprising a control unit for transmitting control pulses to the drive motor such that the rotational speed of the printing cylinder at a time at least one of before and after a printing operation deviates from the rotational speed during the printing operation.  
     
     
         38 . The printing unit according to  claim 37 , wherein the wrapping strip is a continuously moving material web passing between the at least one printing cylinder and the counter-pressure cylinder, and wherein the counter-pressure cylinder moves at the same speed as the at least one printing cylinder during the printing operation, but moves at a deviating speed at a time at least one of before and after the printing operation.  
     
     
         39 . The printing unit according to  claim 37 , wherein the at least one printing cylinder includes at least two printing cylinders in contact with the counter-pressure cylinder.  
     
     
         40 . The printing unit according to  claim 37 , wherein the motor driving the at least one printing cylinder is a stepping motor, wherein the control unit transmits control pulses to the stepping motor at a predetermined constant frequency for a synchronous movement of the at least one printing roller and the material web during the printing operation and at a second frequency for a deviating movement between two printing operations.  
     
     
         41 . The printing unit according to  claim 40 , wherein the control unit includes a memory for storing the predetermined frequencies of the control pulses.  
     
     
         42 . A method for periodically applying print marks to a wrapping strip of the tobacco industry, comprising the following steps: 
 supplying the wrapping strip at a first speed to an operating range of a printing cylinder;    rotating the printing cylinder at a second speed; and applying a print mark to the wrapping strip with the printing cylinder;    wherein the first and second speeds are approximately equal while the print mark is being applied to the wrapping strip, and wherein the first and second speeds deviate from one another at least part of the time while no print mark is being applied to the wrapping strip.    
     
     
         43 . The method according to  claim 42 , further comprising changing second speed periodically.  
     
     
         44 . The method according to  claim 43 , wherein the changing step includes activating a stepping motor with control pulses having an alternating frequency.  
     
     
         45 . The method according to  claim 44 , wherein the activating step includes determining the frequency according to a stored characteristic curve.  
     
     
         46 . The method according to  claim 45 , wherein the activating step includes additionally determining the frequency in accordance with the first speed.