Abstract:
A flexible printing plate with bent suspension legs is secured on a cylinder of a printing press by utilization of a base body located in a cylinder groove. The base body supports flexible clamping elements which can engage the suspension legs. The base body may be formed by a plurality of short base bodies to facilitate removal and replacement of the base body.

Description:
FIELD OF THE INVENTION 
     The present invention is directed to a device for fixing a flexible plate in place on a cylinder of a rotary printing press. The flexible plate has suspension legs that are received in a fastening slit on the cylinder. At least one base body, which receives fastening elements, is situated in the cylinder groove that is located radially inwardly from the fastening slit. 
     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. 
     In this prior device, 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, 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 of the spindle. 
     DE-OS 22 35 119 discloses a device for clamping a printing plate, wherein lead springs are fastened on a pivotable shaft. This shaft is arranged in three stationary bearings. 
     DE 38 12 137 A1 describes a device for fastening a printing plate. Two pivotable fastening elements are seated in a hollow shaft. 
     DE 11 78 442 B1 shows a device for fastening a flexible plate with a base body, wherein a length of the fastening elements is less than a length of the base bodies. 
     EP 0 713 770 A1 describes a device for fastening printing plates by means of leaf springs. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is directed to providing a device 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 cylinder with a fastening slit that terminates in a cylinder groove. The groove is radially inward from the slit and carries at least one base body. Typically, several such base bodies are carried in the cylinder groove. Fastening elements, that engage suspension legs of flexible plates, when these suspension legs are inserted into the cylinder groove, are carried by these base bodies. The lengths of the fastening elements are less than or equal to the lengths of the base bodies in the cylinder axial direction. 
     The advantages to be obtained by the present invention consist, in particular, in that a rugged, simply constructed device, which can be produced cost-effectively, is created. The device in accordance with the present invention can be displaced without the turning of a spindle in only two positions. 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 from the cylinder groove, for example for maintenance purposes, without having to dismount the cylinder from the lateral frame. An automatic plate feeding and removal by means of known devices is possible. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Two preferred embodiments of the present invention are represented in the drawings and will be described in greater detail in what follows. 
     Shown are in: 
     FIG. 1, a device, in accordance with a first embodiment, in cross section in the plate holding position or position of rest, 
     FIG. 2, a device in accordance with FIG. 1 in a plate receiving or operating position, 
     FIG. 3, a section taken along line III—III of FIG. 2 in a partial representation, 
     FIG. 4, a device in accordance with a second embodiment in cross section in the position of rest, 
     FIG. 5, a device, in accordance with the second embodiment, in the operating position, and in 
     FIG. 6, a section taken along line VI—VI of FIG. 4 in a partial representation. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     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 at least one cylinder groove  03  extending in the axial direction of cylinder  01 . At a front edge  04 , pointing in the production direction A of the cylinder  01 , the cylinder groove  03  receives a front, or “leading”, suspension leg  06  of the plate  02 . The plate  02  furthermore has a rear, or “trailing” suspension leg  07 , which is suspended from a second, rear edge  08  of the same cylinder groove  03 . 
     An acute opening angle a, for example up to 45°, is formed between a surface  11  of the cylinder  01  and a first cylinder wall  12  of the cylinder groove  03 . A second groove wall  13 , extending approximately in the radial direction of the cylinder  01 , has an obtuse opening angle β of approximately 95° in respect to the surface  11 . Both edges  04 ,  08 , or 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, in such a way that at least two suspension legs  06 ,  07 , which project into the cylinder groove  03 , can be placed therein next to each other. 
     The cylinder groove  03  can be approximately circular in cross section and it is connected with the surface  11  of cylinder  01  through the fastening slit  09 . Two springs  14 ,  16 , each made of spring steel, and formed as, for example leaf springs, are arranged in the cylinder groove  03  at a spring spacing distance c from each other—for example with distance c corresponding to approximately half of the diameter d of the cylinder groove  03 . A longitudinal axis of the springs  14 ,  16  extends in an axis-parallel direction in respect to the cylinder  01 . A vertical axis e, f of the springs  14 ,  16 , respectively, extends approximately at right angles in relation to the plane of the first groove wall  12 , all as shown in FIG.  1 . 
     Lower or radially inner ends  17 ,  18  of the springs  14 ,  16 , which are remote from the cylinder surface  11 , or the suspension legs, are fastened on an abutment, for example a base body  19  with a cross section of a longitudinally cut tube thus having a channel-shaped cross section, which base body  19  extends in an axis-parallel direction in the cylinder groove  03 . 
     A holding strip  21 , which is fixed on the base body  19 , and on whose lateral faces the lower ends  17 ,  18  of the springs  14 ,  16  are fastened, can also be arranged on the base body  19 . The two upper or radially outer, free ends  22 ,  23 , which are the spring ends on which the force acts, of the springs  14 ,  16  are each bent in a hook shape, and their length is such that they are in an operative connection with the suspension legs  06 ,  07  in the plate holding position or position of rest, again as seen in FIG.  1 . 
     The springs  14 ,  16  can also be made in one piece, i.e. in a U shape. 
     To be in operative connection means that the upper, free ends  22 ,  23  are connected, either frictionally or interlockingly with the suspension legs  06 ,  07 . This frictional connection means that the upper spring end  22  close to the suspension leg  06  presses the front suspension leg  06  against the first groove wall  12 . On the other hand, the interlocking connection means that the upper spring end  23 , which is bent in a hook shape and is close to the rear suspension leg  07 , grips the rear suspension leg  07 , which is provided with holes  24 , with one or preferably several projections of upper spring end  23  being received in several corresponding holes  24 , as shown in FIGS. 1 and 2. 
     A force-transfer element  26  is located in the vicinity of the free upper spring ends  22 ,  23 , and is positioned between the springs  14 ,  16 . This force-transfer element  26  can extend continuously in an axis-parallel direction with the cylinder groove  03  and can be embodied as a rail, a strip or a cylinder. The force-transfer element  26  can be fastened to both springs  14 ,  16 , or only to respectively one spring  14  or  16  or to the holding strip  21 , for example, by means of a third leaf spring, not specifically represented. 
     It is furthermore possible to embody the force-transfer element  26  “discontinuously”, i.e. in the form of a pin, sphere or comb. 
     Viewed in a cross-sectional view of the device, as seen in FIG. 1, an actuating means, for example a hose  27 , which can be filled with compressed air, and which is thus called an air hose, is arranged between the first leaf-shaped spring  14  and the interior wall  28  of the channel-shaped base body  19 . 
     On one of its ends, the hose  27  is provided with a valve, for example, and is charged with compressed air when needed via a line, not represented, to the cylinder journal, and by means of a known rotary lead-in. 
     The elements  14 ,  16 ,  21 ,  26 , which are located in an interior  29  of the base body  19  are collectively called gripping and/or clamping elements, or fastening elements. 
     The channel-shaped base body  19  can be embodied to be C-shaped or U-shaped in cross section, round, oval or polygonal. The cross section of the cylinder groove  03  is matched to the cross section of the base body  19 . 
     The base body  19  has a base body opening  31  opening or pointing in the direction of the fastening slit  09 , through which the elements  22 ,  23  of the gripping and/or clamping elements  14 ,  16  project. 
     If the device is now intended to be brought from the plate holding position or position of rest, shown in FIG. 1, into the plate receiving, or operating position, shown in FIG. 2, the air hose  27  is charged with compressed air. In the course of this, an abutment surface  56  of the air hose  27  rests against the inner wall  28  of the base body  19 , and a force-engagement surface  57  of the air hose  27  rests against the spring  14 . Because of this, a pivot movement of both springs  14 ,  16 , which are kept spaced apart at a distance c by the force-transfer element  26 , takes place, so that the upper legs  22 ,  23  of the springs  14 ,  16  come out of engagement with the suspension legs  06 ,  07  of the plate  02 . The plate  02  can be removed, or exchanged. Following the removal of air from the air hose  27 , the upper ends  22 ,  23  of the springs  14 ,  16  come into operative connection with the suspension legs  06 ,  07  of the plate  02  now positioned on the surface  11  of the cylinder  01 . 
     In accordance with an embodiment depicted in FIG. 3, the base body  19  is divided into several short base bodies  32 ,  33 ,  34  that are adjacent each other in an axis-parallel direction. Each short base body  32 ,  33 ,  34  is releasably connected with the adjoining short base body  32 ,  33 ,  34 , for example by means of a coupling. This coupling can act interlockingly, for example, and can be implemented by means of teeth  36 ,  37  on both ends of each of the short base bodies  32 ,  33 ,  34 . Each short base body  32  to  34 , respectively, has springs  14 ,  16 , at least one force-transfer element  26 , a holding strip  21 , as well as a projection at the upper end  23  of the spring  16 . The air hose  27  is always embodied in one piece and passes through all of the short base bodies  32 , to  34 . Free ends of the first and last short base bodies in the cylinder groove  03  are connected, fixed against relative rotation, with an end coupling element  38 . The end coupling element  38  is fastened, with its portions covering the cylinder groove  03 , to the flanks of the cylinder  01 , for example screwed to it. 
     By using several short base bodies  32  to  34  it is possible to take the plate holding device out of the cylinder groove  03 , for example for maintenance purposes, without it being necessary to dismount the cylinder  03  from the lateral frame. 
     In accordance with a second preferred embodiment which is represented in FIGS. 4 and 5, the gripping and/or clamping elements, which can be moved in the channel-shaped base body  19  or in the short base bodies  32  to  34 , as shown in FIG. 6, and which are interlockingly connected with each other, consist of two strips  39 ,  41  extending parallel with each other. If several base bodies  32 ,  33 ,  34  are provided, a length  132 ,  133 ,  134  of the respective base bodies  32 ,  33 ,  34  is greater than a length  139 ,  141  of the two strips or fastening elements  39 ,  41 . 
     First, radially inner or lower ends  42 ,  43  of strips,  39 ,  41  respectively, are pivotably seated apart from each other at a clear spacing distance g, of, for example, one-sixth or one-eighth of the diameter d of the cylinder groove  03 , in abutments  44 . The abutments  44  can consist of slits  45  arranged in the base body  19 , or in the respective base bodies  32  to  34 , which slits  45  are engaged by portions of the lower or radially inner ends  42 ,  43  of the strips  39 ,  41 . 
     Second, radially upper or free ends  46 ,  47 , that are the force-engagement ends, close to the suspension legs and which are bent off at right angles, of the strips  39 ,  41  are in direct or indirect operative connection with the respectively opposite suspension legs  06 ,  07  of plate  02  and press them against the first, or the second groove wall  12 ,  13  by means of the force of respectively at least one spring or several springs  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 strip  39 ,  41 . 
     An indirect operative connection means that at least one gripping roller  53  for each short base body  32  to  34  is arranged between the upper end  47 , which is beveled in the direction toward the first groove wall  12 , of the strip  41  and the suspension leg or legs  06  resting against the first groove wall  12 . 
     The gripping roller  53  of 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.  6 . Respective beveled 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 a longitudinal section surface of the base body  19 , or prior to that against the suspension leg  07  as seen by referring to FIGS. 4 and 5. 
     An air hose  27  is located between the inner sides  55  of the strips  39 ,  41 , which air hose  27  extends in one piece over the entire length of the cylinder groove  03 . 
     In accordance with a preferred embodiment, a force of pressure F 1  exerted by the spring  48  is smaller than a force of pressure F 2  exerted by the spring  49 . 
     The elements  39 ,  41 ,  48 ,  49 ,  53 , located in the interior  29  of the base body  19  embodied in accordance with the second preferred embodiment are collectively called gripping and/or clamping elements. This also applies to the shorter base bodies  32  to  34 . 
     If the device is intended to be brought from the plate holding position or position of rest, shown in FIG. 4 into the plate receiving, or operating position, shown in FIG. 5, the air hose  27  is charged with compressed air, approximately with six bar. By means of this, the upper ends  46 ,  47  of the strips  39 ,  41 , respectively are moved away from each other against the force F 1 , F 2  of the springs  48 ,  49 . The upper ends or arm  46  of the strip  39 , as well as the gripping roller  53  actuated by the upper end  47  of the strip  41 , are therefore brought out of engagement with the suspension legs  07 ,  06 . 
     In accordance with a preferred embodiment, the air hose  27  is initially charged with an air pressure of approximately 3 bar. Thus, a force of pressure F exerted by the air hose  27  is greater than the force of pressure F 1  of the spring  48  and less than the force of pressure F 2  of the spring  49 . The strip  39  is pivoted, and the arms  46  come out of engagement with the rear suspension legs  07 . Because of the inherent tension of the plate  02 , the suspension leg  07  of the trailing end can pop out of the fastening slit  09  and can be grasped after this. 
     Following a further increase of the air pressure in the air hose  27  to approximately 6 bar, the force of pressure F exerted by the air hose  27  is now also greater than the force of pressure F 2  of the spring  49 , so that the suspension leg  06  is also released. 
     The short base bodies  32  to  34 , as depicted in FIG. 6 can be connected with each other, fixed against relative rotation, by teeth  36 ,  37 . An end coupling element  38  each is fastened at the flanks of the cylinder  01 , the same as in the first preferred embodiment which is depicted in FIG.  3 . 
     In accordance with a further preferred embodiment, which is a part of FIGS. 4 to  6 , it is possible to structure the strip  42  to be slightly longer at its beveled upper edge  47  pointing in the direction of the first groove wall  12 , so that the gripping roller can be omitted. Thus, the axis-parallel extending edge of the upper end  47  of the strip  41  touches the front suspension leg  06  of the plate  02  directly and presses it against the first groove wall  12 . 
     In this case, at least the respectively beveled end  47  of the strip  41  can be made of a resilient spring steel or a corresponding plastic material. 
     While preferred embodiments of a device for fixing 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 the type of flexible plate secured to the cylinder, the drive means for the cylinder, the specific type of printing press and the like could be changed without departing from the true scope and spirit of the present invention which is accordingly to be limited only by the following claims.