Abstract:
The device for mounting and removing blanket strips of a rotary cutting anvil cylinder comprises means for tightening and loosening the ends of at least one blanket strip so as to allow permutation with the other blanket strips of the rotary cutting anvil cylinder. The means for tightening and loosening the ends of a blanket strip include a locking and unlocking element placed in a groove in the periphery of the cylinder body of the rotarycutting anvil cylinder, the groove extending over the entire axial width of the cylinder body. The locking and unlocking element comprises a removable slide moving in the groove. the repective slide includes angled guiding grooves and also grooves all in the shape of linear cams into which fit rollers fixedly attached to at least one jaw which is moveable so as to act on at least one end of the blanket strips. The moveable slide is actuated by atraction device which comprises an adjusting screw fitting into a nut attached to the moveable slide.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to a device for mounting and removing die blankets of a rotary cutting anvil cylinder. The rotary die-cutting operation of the cardboard or corrugated cardboard is well-known and utilizes inter alia, on the one hand, a tool holder cylinder generally consisting of a metal cylinder body on which shells are fixed, preferably made of wood, in which metal cutting rules are inserted and, on the other hand, a cutting anvil cylinder commonly called anvil. This anvil cylinder consists of a metal cylinder body on which blanket strips are mounted, generally made of a plastic such as polyurethane for example. 
   The tool holder cylinder can be covered by various shells having cutting rule configurations according to the shapes and dimensions of the boxes to be cut. The matter to be cut, in this case corrugated cardboard, passes between the tool holder cylinder and the cutting anvil cylinder and, at the time of the die-cutting operation, the metal rules of the tool holder cylinder penetrate more or less deeply into the blanket strips, which causes after a certain number of hours of cutting a wear of some of these blanket strips. 
   The blanket strips are generally mounted side by side over the width of the cylinder body of the anvil cylinder. The cylinder body has a groove extending over its entire width. In order to fix the blanket strips, the ends of them are inserted in the groove arranged in the anvil cylinder by means of a mallet. Each end of the blanket strips can be reinforced by a metal reinforcement, one end having a centering nose and the other a notch into which fits the centering nose. Due to this fixing, the mounting thus carried out is practically permanent and requires a removal by force. 
   The wear of the surface of the blanket strips is not regular over the entire width of the anvil cylinder and, obviously, if the wear interferes with the diecutting or creasing operation of the cardboard, an acceptable surface quality of the die blanket of the anvil cylinder should be restored. 
   Generally, to restore the surface quality, the external diameter of the die blanket of the anvil cylinder is rectified by grinding or any other similar machining. Due to the high production rate of the rotary die-cutting machines, this operation must be frequently repeated and, in addition to causing an important reduction in the productivity of the machine, it involves a significant consumption of blanket strips. 
   SUMMARY OF THE INVENTION 
   The aim of the present invention is to eliminate the aforesaid disadvantages with an anvil cylinder whose design allows to make the restoration operations less frequently, or even to remove them. 
   To this end, the present invention relates to a device for quickly mounting and removing blanket strips of a rotary cutting anvil cylinder characterized in that it comprises means for tightening and loosening the ends of at least one blanket strip so as to allow permutation with the other blanket strips of the anvil cylinder before a significant wear arises. 
   According to an embodiment of the invention, the means for tightening and loosening the ends of a blanket strip consist of a locking and unlocking element placed in a groove arranged in the periphery of the cylinder body of the rotary cutting anvil cylinder, this groove extending over the entire width of the cylinder body. 
   According to a preferred embodiment of the invention, the locking and unlocking element comprises a removable slide moving in the groove extending across the cylinder body, this removable slide including guiding grooves and grooves in the shape of linear cams into which fit rollers fixedly attached to at least one jaw which is removable so as to act on at least one end of the blanket strips. 
   According to another embodiment of the invention, the removable slide is actuated by means of a traction device comprising an adjusting screw fitting into a nut attached to the lower part of the removable slide. 
   According to another preferred embodiment of the invention, the traction device comprises a cylinder for actuating the removable slide. According to an embodiment of the invention, the traction device is placed in a groove arranged at one end of the cylinder body. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings illustrate, schematically and by way of example, an embodiment of the device for mounting and removing blanket strips of a rotary cutting anvil cylinder being subject of the invention. 
       FIG. 1  is a schematic view of a rotary cutting anvil cylinder, 
       FIG. 2  is a plan view of a removable slide, 
       FIG. 3  is a view in partial section according to III—III of  FIG. 1  illustrating a locking and unlocking device with only one jaw in tightening position of the blanket strips, 
       FIG. 4  is a view in partial section according to III—III of  FIG. 1  illustrating a locking and unlocking device with two jaws in tightening position of the blanket strips, 
       FIG. 5  is a view in partial section according to III—III of  FIG. 1  illustrating the locking and unlocking device with two jaws in loosening position of the blanket strips, 
       FIG. 6  is a perspective view of a traction device, 
       FIG. 6   a  is a perspective view of one embodiment of a traction device, 
       FIG. 6   b  is a perspective view of an alternate embodiment of a fraction device, 
       FIG. 7  is a view according to A of FIG.  5 . 
       FIGS. 8   a  to  8   d  schematically illustrate the permutation sequences of the blanket strips. 
   

   DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIG. 1  is a schematic view of a rotary cutting anvil cylinder comprising a cylinder body  2  on which are rolled up blanket strips  3  kept at each end of the cylinder body  2  by means of stop discs  4 . The cylinder body  2  comprises a groove  5  extending over its entire axial direction. The ends  6 ,  7  of the blanket strips  3  fit into a tightening and loosening means consisting of a locking and unlocking device  8  (see  FIGS. 3 ,  4  and  5 ) placed in the groove  5 . 
     FIG. 2  is a plan view of a removable slide  9  used in the locking and unlocking device  8 . This removable slide  9  comprises guiding grooves  10  and grooves in the shape of linear cams  11  into which fit rollers  12 ,  13  and  14  (see  FIGS. 3  to  6 . 
     FIG. 3  is a view in partial section according to III—III of  FIG. 1  illustrating a locking and unlocking device  8 , with only one jaw  16 , in tightening position of the blanket strips  3 . The locking and unlocking device  8  comprises a removable slide  9   a  which includes grooves in the shape of linear cams  11   a  into which fit the rollers  14   a . The rollers  14   a  are mounted on an axis  17  fixedly attached to the jaw  16 . This jaw  16  is provided with guiding rods  18  which can slide in a small bar  19  kept in the groove  5   a  by means of screws  20 . The end  6   a  of the blanket strip  3  hangs on the nose  16 a of the jaw  16 . The other end  7   a  of the blanket strip  3  is hung on the nose  25   a  of a fixed small bar  25  kept in the groove  5   a  by means of screws  26 . The ends of the strips, depending on manufacture, can be reinforced by stiffeners  23  and  24 . The removable slide  9   a  includes at one end a traction device consisting of a nut  27  crossed by an adjusting screw  28 . This nut  27  is attached to the lower part of the removable slide  9   a  by means of screws  29 . 
   Thus, when actuating the adjusting screw  28  of the removable slide  9   a  in one direction, the jaw  16  will move in the direction of arrow  30  in order to loose the end  6   a  of the blanket strip  3 . This displacement of the jaw  16  is obtained through action of the grooves  11   a  in the shape of linear cams, arranged in the removable slide  9   a  on the rollers  14   a , fixedly attached to the jaw  16 . The displacement of the jaw  16  will be chosen so that the end  6   a  of the blanket strip  3  can be released from the nose  16   a  and this blanket strip easily and without wear removed. By turning the adjusting screw  28  in the opposite direction, after having replaced either a blanket strip  3  to be permuted, or a new blanket strip  3 , the jaw will move in the opposite direction of arrow  30  what will tighten the end  6   a  of the blanket strip  3  against its end  7   a.    
   It is to be noted that this removable slide  9   a  includes grooves in the shape of linear cams  11   a  on only one part of its surface since only one jaw  16  exists. An unspecified number of locking and unlocking devices  8  are possible in the width, independent of the number of blanket strips  3  distributed over the width of the cylinder body  2 . 
     FIG. 4  is a view in partial section according to III—III of  FIG. 1  representing a locking and unlocking device  8  with two jaws in tightening position of the blanket strips  3 . The locking and unlocking device  8  comprises a removable slide  9  which includes grooves in the shape of linear cams  11   a  into which fit rollers  13  and  14  (see also FIG.  2 ). The rollers  13  are mounted on an axis  31  driven in the jaw  32 . This jaw  32  includes a profile in the shape of a toothing  33  acting jointly with a combined profile  34  arranged in the fixed small bar  35  kept in the groove  5  of the cylinder body  2  by means of screws  36 . The function of these profiles  33 ,  34  is to always support the blanket strip  3  if a cutting rule faces the part of circumference corresponding to the zone between the rear of the jaw  32  and the front of the small fixed bar  35 . Obviously, if a rectilinear rear part of the jaw  32  and a rectilinear front part of the small fixed bar  35  is chosen, a slit would be created when tightening at the level of which the blanket strip  3  would not be supported. The end  6  of the blanket strip  3  can be reinforced by a stiffener (not shown) and hangs on the nose  32   a  of the jaw  32 . The other end  7  of the blanket strip  3  can also be reinforced by a stiffener (not shown) and hangs on the nose  37   a  of a second jaw  37 . The jaw  37  also includes a profile in the shape of a toothing  38  acting jointly with a combined profile in the shape of a toothing  39  arranged in the small fixed bar  40  kept in the groove  5  of the cylinder body  2  by means of screws  41 . The toothings  38  and  39  have the same function as the toothings  33  and  34 . The rollers  14 , associated with the jaw  37 , fit into the grooves in the shape of linear cams  11  and are mounted on an axis  42  kept in the jaw  37 . 
   The removable slide  9  includes at one end a traction device  44  which will be described more in detail by means of  FIGS. 6 and 7 . When actuating the traction device  44 , the jaw  32  moves in the direction of arrow  43  in order to tighten the end  6  of the blanket strip  3 . This displacement of the jaw  32  is obtained through action of the grooves in the shape of linear cams  11   a , arranged in the removable slide  5 , on the rollers  13 , fixedly attached to the jaw  32 . The movement of the removable slide  9  will also simultaneously move the jaw  37  but in the direction of arrow  45 , this by action of the grooves in the shape of linear cams  11  on the rollers  14 . The jaws  32  and  37  as well as the removable slide  9  are guided by means of rollers  12  fitting into the guiding grooves  10 . The rollers  12  are mounted, so as to be turnable, on the cylinder body  2  by means of screws  46 . 
   The solution with two jaws  32  and  37  allows to loose and tighten the ends  6  and  7  of the blanket strips  3  by shortening the displacement of the removable slide  9  as well as of the jaws  32  and  37 . An unspecified number of locking and unlocking devices  8  in the width are possible, independent of the number of blanket strips  3  distributed over the width of the cylinder body  2 . 
     FIG. 5  is a view in partial section according to III—III of  FIG. 1  illustrating the locking and unlocking device  8  with two jaws in loosening position of the blanket strips. In this figure, the reference numerals are the same as those used in relation to FIG.  4 . However, when actuating the traction device  44  in the opposite direction, the jaw  32  will move in the direction of arrow  47  in order to loosen the end  6  of the blanket strip  3 . The movement of the removable slide  9  will also simultaneously move the jaw  37  in order to loosen the end  7  of the blanket strip  3  but in the direction shown by arrow  48 , this by action of the grooves in the shape of linear cams  11  on the rollers  14 . The displacement of the jaws  32  and  37  will be chosen so that the ends  6  and  7  of the blanket strip  3  can be released from the noses  32   a  and  37   a  and this blanket strip  3  easily and without wear removed. 
   This solution with two jaws  32  and  37  allows to tighten and loose the ends  6  and  7  of the blanket strips  3  by shortening the displacement of the removable slide  9  as well as of the jaws  32  and  37 . An unspecified number of locking and unlocking devices  8  in the width are possible, independent of the number of blanket strips  3  distributed over the width of the cylinder body  2 . 
     FIG. 6   a  is an exploded view, in partial section, of a traction device  44  arranged at one end of the rotary cutting anvil cylinder  1 . This traction device  44  comprises an adjusting screw  49  guided in a bearing plate  50  fixed in a housing  51  of the rotary cutting anvil cylinder  1  by means of screws  52  and  53 . This adjusting screw  49  is positioned in the bearing plate  50  by means of a set collar  54 . The adjusting screw  49  fits into a nut  55  attached to the lower part of the removable slide  9  by screws  56  and  57 . The nut being fitted in a recess  61 . Thus, by rotating the adjusting screw  49  in one direction or the other, the ends  6 ,  7  of the blanket strips  3  are tightened or loosened. Obviously, the traction device  44  can be replaced by any other element able to move the removable slide  9 , e.g. a pneumatic cylinder  63 , shown in  FIG. 6   b .  FIG. 6   b  is otherwise the same as  FIG. 6   a  and the same reference numerals are used. 
     FIG. 7  is a view in the direction A of  FIG. 5  represented without blanket strips  3 . In this figure, the various components have the same reference numerals as those used in relation to the description of  FIGS. 4 ,  5 ,  6   a  and  6   b.    
     FIGS. 8   a  to  8   d  schematically illustrate the permutation sequences of the blanket strips  3 . In  FIG. 8   a , the jaws  32  and  37  are in loosened position (see FIG.  5 ). It is thus possible to remove the blanket strip  3  as shown by arrow  58 . The blanket strips  3   a  to  3   c  are also in a loosened position which allows them to move in the direction of arrows  59  (see  FIG. 8   b ). Once the blanket strips  3   a  to  3   b  are displaced, the blanket strip  3  can be repositioned, as shown by arrow  60 , at the place previously occupied by the blanket strip  3   c  (see  FIG. 8   c ). The blanket strips  3  to  3   c  having been permuted, the traction device  44  will be acted and the jaws  32  and  37  will come into the tightening position as shown in FIG.  4 . Obviously, this solution offers many possibilities to the user who can choose to permute any blanket strip  3  to  3   c  according to their wear without damaging the blanket strips  3  to  3   c . The identical symmetrical shape of the ends of the strips  3  moreover allows to rotate themselves, the front edge becoming then the rear edge, for better distributing the wear.