Abstract:
The rotation angle position of a moveable component, such as a cylinder, is detected or determined through a method in which the detected rotation angle position is modified using a correction value when the moveable component is in a second position.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a method for determining an angle of rotation position of a movable cylinder of a printing press. 
     DESCRIPTION OF THE PRIOR ART 
     A device for an angular position sensor is known from DE 196 14 818 A1, wherein a stator of the angular position sensor is arranged at a fixed angle in respect to the lateral frame. 
     DE 197 20 952 A1 describes a method for compensating a rotating movement superimposed on the rotating movement of a cylinder because of an eccentric movement. The compensation is performed by a control circuit, which is supplied with the actual angle of rotation of the cylinder in respect to an eccentric device, as well as with the actual angle of rotation of the eccentric device, or with an angular function derived therefrom. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is directed to providing a method for determining an angle of rotation of a movable cylinder of a printing press. 
     In accordance with the invention, this object is attained by using an angle of rotation position sensor. A first angle of rotation of the component in a reference position is determined. In a second position of the component, a second angle of rotation is also determined. A difference between the two is used as the correction value for determining the actual angular position of the component in its second position. 
     In connection with the drive mechanism in accordance with the present invention for cylinders of a printing press, it is possible in an advantageous manner to arrange an angle of rotation position sensor in any arbitrary manner, i.e. an angle of rotation position of the angle of rotation position sensor in respect to the lateral frame need not be constant during the movement of the cylinder. 
     It is also possible to remove errors, for example as a result of production-related tolerances. 
    
    
     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 schematic representation of a longitudinal section through a bearing of a cylinder, 
     FIG. 2, a schematic representation of the lateral view in accordance with FIG. 1, and in 
     FIG. 3, a schematic representation of a block wiring diagram of a drive control. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 represents a longitudinal section of a rotating component of a printing press, for example a cylinder  1 , which is rotatably driven around its longitudinal axis, called the axis of rotation  2  of the cylinder in what follows, and which is pivotable around a pivot axis  5 . The cylinder  1  is rotatably seated in an eccentric bushing  3  by a bearing  4  on its two outer cylinder journals, only one of which outer cylinder journals is represented in FIG.  1 . The eccentric bushing  3  itself is rotatably seated in a sliding bearing in a machine frame  6 . The cylinder  1  is pivoted in a generally known manner about the pivot axis  5  by operation of the eccentric bushing  3 . The pivot axis  5  is also the axis of rotation of the eccentric bushing  3  in the machine frame  6 . The distance between the axis of rotation  2  of the cylinder and the pivot axis  5  is the eccentricity e. 
     An angle of rotation position sensor  9  has been fastened, in a manner fixed against relative rotation in respect to the axis of rotation  2  of the cylinder, on the outermost journal end of the cylinder  1  as seen in FIG.  1 . The angle of rotation position sensor  9  is comprised of an inner ring  10  and a circular first measuring disk  13 , which is rigidly connected with it. The application, of the inner ring  10  on the journal of the cylinder  1  in a manner fixed against rotation, is indicated by a cotter pin  11 . The first measuring disk  13  has a known circular graduation with a multitude of lines extending in the radial direction. An outer ring  14 , which is slidingly rotatably seated on the inner ring  10 , and with which a second circular disk  15  is rigidly connected, encloses the inner ring  10 . This second or scanning disk  15  is provided with a multitude of photo elements for scanning the line graduation of the first or measuring disk  13 . The relative angle of rotation position of the first or measuring disk  13  with respect to the second or scanning disk  15 , which is therefore used as a reference (relation) for the angle of rotation position of the first measuring disk  13 , is determined by means of photo-electrical scanning, which photo-electric scanning merely represents a preferred embodiment of the scanning process, but to which the invention is not exclusively limited, and by the angle of rotation position of the cylinder  1  in respect to the outer ring  14 , which is used as the reference element  14  and which has the second or scanning disk  15 , called reference disk  15  in what follows. The outer ring  14  and the reference disk  15  constitute a reference element for the angular position sensor  9 . 
     A support arm  30  is seated, pivotable around a pivot axis  31 , on the machine frame  6 . On its end remote from the pivot axis  31 , the support arm  30  has an elongated recess  32 , which, as seen in FIG. 2 is embodied as a simple elongated hole in the preferred embodiment. The pivot axis  31  of the support arm  30  extends parallel with the axis of rotation  2  of the cylinder. A rigid guide element  17 , which is rigidly connected with the reference element  14 , is force-guided in the course of a pivot movement of the cylinder  1 . The reference element  14  is maintained in its zero position during a printing operation by means of the forced guidance, in particular during pivoting of the axis of rotation  2  of the cylinder. 
     The arrangement in accordance with FIG. 1 is represented in FIG. 2 in a front view on the cylinder  1 . By operation of a motor M or a working cylinder, which acts on the eccentric bushing  3 , the cylinder  1  is pivoted around the pivot axis  5 , which simultaneously represents the pivot axis of the cylinder  1 , by an angle α from its zero position, namely the printing position. In the course of this pivot movement, the axis of rotation  2  of the cylinder describes an arc s of a segment of a circle and moves into the pivoted-away position indicated by  2 ′, as seen in FIG.  2 . 
     In the preferred embodiment in accordance with FIGS. 1 and 2, the reference element  14  is rigidly connected with the guide element  17 , which is force-guided at a close lateral distance in the recess  32  of the support arm  30 . In the preferred embodiment the guide element  17  is designed as a simple square bolt, which is guided, sliding in the recess  32 , in a purely translatory manner; tilting is prevented by this. In the course of pivoting the cylinder  1 , the angle of rotation position of the cylinder  1  does not change by the amount of the pivot angle α of the cylinder  1 , but by the amount of the smaller pivot angle β of the support arm  30 . 
     Thus, the cylinder  1  can be pivoted out of a first operating position, for example “print ON”, into a second operating position “print OFF”. If the cylinder  1  is arranged to be not rotatable, for example in relation to the eccentric bushing  3 , the rotor  13  and the stator  15  of the angle of rotation position sensor  9  rotate in respect to each other. 
     A second actual value β  2 , which is in relation to the second operating position, is determined. A correction value is fixed from a difference between the actual value β  1 , determined in a first operating position, and the actual value β  2 . If the cylinder is now driven in the second operating position, a computer  33  is supplied with the previously determined correction value and corrects the actually determined actual value by this correction value during the operation of the cylinder in its second operating position. This means that the actual value of the rotating component  1 , as well as the correction value are determined by a single angle of rotation position sensor  9 . 
     This correction value can also be calculated from the geometric relationships and can be determined without a measurement by means of an angle of rotation sensor. 
     Thus, a pre-calculated correction value is supplied to the computer  33  as a “manually” determined constant value. 
     It is also possible to fix a plurality of correction values for the entire course between the first and second operating positions. For this purpose, it would be possible, for example, to determine correction values as a function of the chronological course of the position changes of the cylinder  1 , i.e. a function of correction values depending on the time. 
     It is also possible to assign a position sensor to the cylinder  1  which determines a position of the eccentric bushing  3 , and therefore a position of the axis of rotation of the cylinder in respect to the machine frame  6 . By means of this, it is possible to determine correction values as a function of the position of the cylinder  1 . 
     It is also possible to determine the correction values as a function of time, or of the position, either in discrete steps or continuously. 
     The position of the cylinder is understood to mean the position of the axis of rotation  2  of the cylinder  1  in relation to the machine frame  6 . 
     An output element  34  is connected downstream of the computer  33  for controlling a drive motor  36  for driving the cylinder  1 . 
     While a preferred embodiment of a method for detecting a rotation angle position of a moveable cylinder of a printing machine in accordance with the present invention has 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 drive for the cylinder 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.