Abstract:
A plurality of flexible printing plates can be secured on a peripheral surface of a cylinder in a rotary printing press. The cylinder has several plate end clamping devices that can be actuated to release only selected ends of the flexible plates. This facilitates the sequential release or securement of the plates in a desired order.

Description:
FIELD OF THE INVENTION 
     The present invention is directed to a method for fastening a flexible plate on a cylinder of a rotary printing press. The flexible plate has angled suspension legs which are placed in a suspension slit on the cylinder surface. A cylinder groove underlies the slit. Inflatable air hoses and springs are used in conjunction with clamping devices that can be operated in a sequential manner. 
     DESCRIPTION OF THE PRIOR ART 
     A device for fixing a flexible printing plate on the forme cylinder of a rotary printing press having at least one cylinder groove extending in the axial direction is known from DE 43 35 140 C1. 
     A first, or leading suspension leg, which is beveled at an acute angle, is suspended at an edge of the first groove wall of the cylinder groove of the forme cylinder. A second, or trailing, suspension leg can be placed against the second groove wall, which second groove wall is extending approximately in the radial direction of the forme cylinder, of the cylinder groove. The cylinder groove contains a spindle which is pivotable around its axis. Two leaf springs, each of which is distributed over the width of the printing plate, are fastened on the spindle and can be brought into, or out of contact with the suspension legs in the course of pivoting the spindle. 
     DE 38 12 137 A1 describes a device for fastening a printing plate, wherein two pivotable fastening elements are seated in a hollow shaft. 
     EP 0 606 604 B1 discloses a device for the interlocked fastening of a printing plate. In this case, clamping strips are actuated by means of an air hose. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is directed to providing a method for fastening a flexible plate on a cylinder of a rotary printing press. 
     In accordance with the present invention, this object is attained by providing the plate receiving cylinder with a plate end receiving suspension slit that overlies a cylinder groove. An inflatable air hose and springs located in the cylinder groove are utilized to shift plate end clamping devices between plate holding and plate release positions. The air hose can be inflated to two different pressure levels. The spring forces exerted by the various springs may also differ. This allows several plates to be released in a sequential manner. 
     The advantages to be obtained by the present invention consist, in particular, in that a rugged, simply constructed device is created, which can be produced cost-effectively. The device in accordance with the present invention can be displaced without the turning of a spindle in three positions. The device is particularly suited to clamping and releasing of several plates arranged at the circumference of a cylinder. A further advantage of the present invention lies in that in its axial extension it can consist of several short base bodies. It is possible, because of this, to remove the device laterally piece by piece from the cylinder groove, for example for maintenance purposes, without having to dismount the cylinder from the lateral frame. Automatic plate feeding and removal by the use of known devices is possible. 
    
    
     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 cylinder in cross section in the plate holding position with two plates clamped on the circumference by use of two devices in accordance with the present invention, 
     FIG. 2, a representation of a device in accordance with FIG. 1 in an enlarged scale, 
     FIG. 3, a representation analogous to FIG. 2, in a first release position, 
     FIG. 4, a representation analogous to FIG. 2, in a second release position, and in 
     FIG. 5, a section V—V in accordance with FIG.  2 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     For receiving flexible plates  02 , a cylinder  01 , for example, a plate or a rubber blanket cylinder of a rotary printing press, is provided with two cylinder grooves  03 ,  59  each extending in the axial direction for receiving two flexible plates  02 ,  58  located on the circumference of cylinder  01 , as seen in FIG.  1 . At a front edge  04  pointing in the production direction A of the cylinder  01 , each cylinder groove  03 ,  59  receives a front, or “leading”, beveled suspension leg  06 ,  61  of the plate  02 ,  58 . Each plate  02 ,  58  furthermore has a rear, or “trailing” beveled suspension leg  07 ,  62 , which is suspended from a second, rear edge  08  of the same cylinder groove  03 ,  59 . 
     An acute opening angle α, for example up to 45°, is formed between the peripheral surface  11  of the cylinder  01  and a first cylinder wall  12  of the cylinder groove  03 ,  59 . A second groove wall  13 , extending approximately in the radial direction of the cylinder  01 , has an obtuse opening angleβof approximately 95° with respect to the cylinder&#39;s peripheral surface  11 . Both edges  04 ,  08 , which are also vertex points of the opening angles α, β are separated by a fastening slit  09 . 
     The fastening slit  09  is embodied, in its inner width b, in such a way that at least two suspension legs  06 ,  62 , or  07 ,  61 , which all project into the cylinder groove  03 ,  59 , can be placed therein next to each other, as seen most clearly in FIG.  1 . 
     The plates  02 ,  58  can be embodied in the form of flexible printing plates, for example. Also, several plates can be placed side by side. The plates can also be provided as flexible support plates with rubber blankets arranged on them. 
     The cylinder groove  03  can be approximately circular in cross section. It is connected with the cylinder peripheral surface  11  through the fastening slit  09 . 
     Each cylinder groove  03 ,  59  receives a clamping device  14 ,  16 , both of which are embodied the same and both of which are arranged in a base body  19 . Each base body  19  has the form of a longitudinally cut tube so as to be channel-shaped, which tube extends in an axis-parallel direction in the cylinder groove  03 ,  59  and points with its opening  31  generally in the direction toward the first groove wall  12 , or in the direction of the fastening slit  09 . 
     The channel-shaped base body  19  can be embodied to be C-shaped, U-shaped, round, oval or polygonal in cross section. The cross section of the cylinder groove  03  is matched to the cross section of the base body  19  which is received in the cylinder groove  03 , as seen each of FIGS. 1-4 . 
     In accordance with an embodiment which is depicted in FIG. 5, the base body  19  is divided in the axial-parallel direction into several short base bodies  32 ,  33 ,  34 . Each short base body  32 ,  33 ,  34  is releasably connected with its adjoining short base body  32 ,  33 ,  34 , for example by a coupling. Such a coupling can act interlockingly, for example, and can be implemented by sets of teeth  36 ,  37  at both ends of each of the short base bodies  32 ,  33 ,  34 . 
     A free end of the first and last short base body in the cylinder groove  03 ,  59  is connected, fixed against relative rotation, with an end coupling element . With its portions covering the cylinder groove  03 ,  59 , the end coupling element is fastened on the flanks of the cylinder  01 , for example screwed to it. 
     Because of the employment of several short base bodies  32  to  34 , the device can be taken out of the cylinder groove  03 ,  59 , for example for maintenance purposes, without it being necessary to remove the cylinder  01  from the lateral frame. 
     Movable gripping and/or clamping elements are arranged in each base body  19 , or short base bodies  32  to  34 , which movable gripping and/or clamping elements consist of two strips  39 ,  41 , which extend parallel with each other. First, or lower ends  42 ,  43  of strips  39 ,  41  are pivotably seated apart from each other at a clear distance g, of, for example, one-sixth or one-eighth of the diameter d of the cylinder groove  03 ,  59 , in abutments  44  as seen in FIG.  3 . The abutments  44  can consist of slits  45  arranged in the base body  19 , or in the respective short base bodies  32  to  34 , which slits  45  are engaged by portions of the lower ends  42 ,  43  of the strips  39 ,  41 , as seen most clearly in FIGS. 2,  3  and  4 . 
     Second, or upper ends  46 ,  47 , defined as force-engagement ends of the strips  39 ,  41 , are situated close to the suspension legs and are bent off approximately at right angles, as seen in FIGS. 2 and 3. These upper ends  46 ,  47  extend from the interior  29  of the base body  19 , or the short base bodies  32  to  34  and are in direct or indirect operative connection with the respectively opposite suspension legs  06 ,  62 , or  07 ,  61  of the plates  02 ,  58 . They press these plate ends against the first, or the second groove wall  12 ,  13  by using the force of respectively at least one spring  48 ,  49 , for example a pressure spring. The pressure springs  48 ,  49  are respectively arranged between the inner wall  28  of the base body  19  and the exteriors  51 ,  52  of the strips  39 ,  41 . 
     An indirect operative connection means that at least one roller body, for example a gripping roller  53 , for each short base body  32  to  34  is arranged between the upper end  47 , beveled in the direction toward the first groove wall  12 , of the strip  41  and the suspension leg or legs  06 , or  61 , resting against the first groove wall  12 . 
     The gripping roller  53  for each short base body  32  to  34  lies in a cutout  54  located at the upper end  46 , which is near the suspension leg, of the strip  39  as seen in FIG.  5 . Beveled or angled arms of the upper end  46  of the strip  39  remain on both sides of the cutout  54  and press against the second groove wall  13 , or against the suspension leg  07 ,  62  inserted between the second groove wall  13  and the upper end  46  of the strip  39 , as seen in FIGS. 1 and 2. 
     An air hose  27  is located between the inner walls  55  of the strips  39 ,  41 , which air hose  27  extends in one piece over the entire length of the cylinder groove  03 . The air hose  27  extends in this way through the base body  19 , or the short base bodies  32  to  34 . At one of its ends, the air hose  27  is provided with a valve and is charged with compressed air, when needed, via a line, not specifically represented, to the cylinder journal connected with it and by a known rotary inlet. 
     A force of pressure F 1  exerted by the spring  48  is greater than a force of pressure F 2  exerted by the spring  49 . 
     The previously named elements  39 ,  41 ,  48 ,  49 ,  53 , located in the interior  29  of the base body  19  are called gripping and/or clamping elements. This also applies with respect to the short base bodies  32  to  34 . 
     A method for releasing only a first plate  02 , which is one of two flexible plates  02 ,  58  fastened on the circumference of the cylinder, proceeds as follows: the air hose  27  of the first clamping device  14 , shown in FIG. 1, is charged with compressed air at a pressure of approximately four bar. By means of this, the strips  39 ,  41  are pivoted into a first release position X against the force F 1 , F 2  of the springs  48 ,  49 , as seen in FIG.  3 . All clampings are released. The rear suspension leg  07  of the plate  02  snaps out of the fastening slit  09  because of its inherent tension. The front suspension leg  61  of the second plate  58  is held in place at the front edge  04  of the cylinder groove  03 . The air pressure in the hose  27  of the clamping device  14  is then removed. 
     Now, the air hose  27  of the second clamping device  16  is charged with compressed air at approximately two bar. Because of this, as depicted in FIG. 4, only the strip  41  is pivoted against the force F 2  of the weaker spring  49 , so that only the front suspension leg  06  of the plate  02  is released into a second release position Y. The rear suspension leg  62  of the second plate  58  remains clamped, because the spring  48  with the greater force of pressure F 1  does not yield under the second, lower pressure provided to the air hose  27 . 
     Clamping of plates  02  or  58  takes place in the reverse sequence. 
     It is also possible to fasten three or more plates having the corresponding number of clamping devices on the cylinder  01 . 
     While a preferred embodiment of a method and devices for fastening a flexible plate, 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 various 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.