Patent Publication Number: US-6339988-B1

Title: Cylinder with a rubber cover

Description:
FIELD OF THE INVENTION 
     The present invention relates to a cylinder with a rubber covering, as well as to a device for applying the rubber covering. 
     DESCRIPTION OF THE PRIOR ART 
     It is known to coat a cylinder with rubber, for example by vulcanizing. 
     It is disadvantageous here that it is necessary to finish the surface of the rubber covering, for example by grinding. This, in turn, leads to relief formations on the surface of the rubber covering, so that irregularities are caused when transferring liquid or pasty materials. 
     EP 0279295 A2 describes an inking system of a printing press, wherein an inking roller is provided with a rubber blanket. 
     DE 19517653 A1 discloses a roller for a printing press, whose basic body is enclosed in a hose made of an elastomeric material. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is based on providing an inking or dampening agent roller with a rubber coating, as well as to a device for applying the rubber coating. 
     In accordance with the present invention, this object is attained by the provision of an inking and dampening agent roller having a roller body with a rubber covering. The covering consists of a finite rubber blanket whose entire underside is adhesively bonded to the roller body. A joint line formed by the start and end of the rubber covering is angled with respect to the axis of rotation of the roller. 
     The advantages to be obtained by the present invention lie, in particular, in that an essentially homogeneous surface of the rubber covering fastened to the basic roller body is achieved. This, in turn, has the result that the even transfer of pasty or liquid materials is assured. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A preferred embodiment of the present invention is represented in the drawings and will be described in greater detail in what follows. Shown are in: 
     FIG. 1, a cross sectional view with a schematic representation of an ink application roller with a rubber covering in a short inking system, as well as a device for applying the rubber covering; 
     FIG. 2, a view from above of the roller in FIG. 1 in an enlarged representation, and in 
     FIG. 3, an enlarged detail in accordance with FIG.  1 . 
    
    
     DESCRIPTION  0 F THE PREFERRED EMBODIMENT 
     A short inking system  1  for a rotary printing press consists, for example, of a printing or rubber blanket cylinder, not specifically represented, and a forme cylinder  2 , to which pasty ink is transferred from a screen roller  4  by means of an ink application roller  3 , as depicted in FIG.  1 . The screen roller  4  is supplied with ink by a chamber doctor blade installation  6 . An ink collecting pan  7  is arranged underneath the chamber doctor blade installation  6 . The above mentioned elements are seated fixed in a lateral frame, not specifically shown. 
     The ink application roller  3 , hereafter referred to as roller  3 , consists of a basic roller body  8  with two shaft journals  9 , which rotate around an axis of rotation  11 , as may be seen in FIGS. 1 and 2. A self-adhesive rubber blanket  13  of a thickness “b”, for example, of 2.3 mm, is situated on the entire surface or surface area  12  of the basic roller body  8 . A double-sided adhesive foil, or an application of adhesive of a thickness of approximately 0.3 mm can be provided here. By means of this adhesive or adhesive foil it is achieved that the rubber blanket  13  is glued on its entire underside on the surface area  12 . 
     The rubber blanket  13  is envelope-like and has a start  14  and an end  16 . After having been applied to the roller  3 , the start  14  and the end  16  meet along a separation or joint line  17  and may form a butt joint. Referred to an unrolled rubber blanket  13 , this joint line  17  extends at an angle α in relation to a line  18  extending parallel to the axis of rotation  11  of the basic roller body  8 , as may be seen in FIG.  2 . The angle α lies between greater than zero degrees and six degrees, and preferably at three degrees. 
     In accordance with further preferred embodiments, the start  14  and the end  16  of the rubber blanket  13  can overlap in the form of an offset joint or a tapered overlap joint. For this purpose, the start  14  and the end  16  each have tabs  21 ,  22 , which are designed to be of reduced thickness, for example of five to ten millimeters, and which are placed on top of each other in a joint area  19  as seen most clearly in FIG.  3 . The rubber blanket material is known and is commercially available for use with a rubber blanket cylinder in offset rotary printing presses. 
     The rubber blanket  13  is applied as follows: a rubber blanket support, for example a table  23 , is made of a profiled iron frame having two spaced apart longitudinal guides  24 , only one is represented , which are connected by means of three transverse profiles  26 ,  27 ,  28 . 
     The table  23  is covered on its surface, for example with sheet metal  29 . The transverse profiles  26  and  27  are arranged directly to the left and right under the roller  3 , so that in this strip-shaped area a special resilient effect and good adaptation to the radius is achieved by means of the sheet metal  29 . 
     The table  23  is pivotably supported by means of bolts  31  in the not represented lateral frame of the rotary printing press at about half its length “ 1 ”. As depicted in FIG. 1, a rubber blanket  13 —shown in dashed lines—is placed on the table  23  with the side coated with adhesive facing up. A detent strip for the start  14  of the rubber blanket  13  can also be provided parallel with the transverse profiles  26 ,  27 , but on the side of the sheet metal  29  opposite to profiles  26  and  27   
     After the roller  3  has taken up a correct register position, the end  32  of the table  23  which is remote from the roller is pushed into a lower position D. The roller is rotated at creep speed in the clockwise direction E until, after a complete revolution of the roller  3 , the rubber blanket  13  has been completely applied to the basic roller body  8 . 
     Thereafter, the table  23  is pivoted upward in the direction C, or respectively lifted out at the bolts  31 . A quick-setting adhesive, for example, is applied in the axis-parallel direction between the strip-shaped tabs  21 ,  22 , and the facing sides of the tabs  21 ,  22  are placed on top of each other and caused to adhere by pressing them down for approximately 10 to 20 seconds. The pressing can take place, for example, in that the table  23  is turned by 180°, and is re-suspended from the bolts  31  in such a way that the end  32  is underneath the roller  3 . In the course of this, a strip  33  of foam rubber can be pressed on the joint area  19 . 
     If the joint line extends at an angle α in respect to the line  18 , the joint area  19  is enlarged to form an even wider joint area  34 . 
     In accordance with another preferred embodiment which is not specifically represented table  23  can also be arranged to be movable by means of a frame, i.e. not fixed in the lateral frame. 
     To fasten or position the rubber blanket  13  at the correct register means that the joint area  19 , or respectively  34 , of the cylinder  3  corresponds, as much as possible, with a print-free strip, for example a cylinder channel  36  of the plate cylinder  2 . It is advantageous if the circumferential width of the cylinder pit  36  is greater than the joint area  34 . 
     The roller  3  can be used as a rubberized inking roller or as a rubberized damping agent roller with dampening systems. In this case, the roller  3  can be preferably placed directly against a forme cylinder, for example the plate cylinder  2 . 
     The hardness of the rubber blanket is 65 to 70 Shore. While preferred embodiments of a cylinder with a rubber cover and a device for applying the cover in accordance with the present invention have been set forth fully and completely hereinabove, it will be apparent to one of skill in the art that a number of changes in, for example, the overall size of the cylinder, the specific type of rotary printing press and the like could be made without departing from the true spirit and scope of the present invention which is accordingly to be limited only by the following claims.