Patent Publication Number: US-7594884-B2

Title: Folding device

Description:
This claims priority to the French patent application number 05 13382, filed Dec. 27,2005, and hereby incorporated by reference herein. 
     The present invention relates to a folding device, in particular for a rotary press, capable of folding signatures, of the type comprising:
         a blade cylinder which is provided with at least one blade which is capable of cutting a printed web of material,   a counter-pressure cylinder which is provided with at least two counter-pressure elements which together define an axial gap, the blade pressing on the two counter-pressure elements during the cutting operation,   a conveying element which extends around the counter-pressure cylinder, which at least partially surrounds the blade cylinder, and which is capable of conveying the web and/or a signature cut from the web at least downstream of the cutting location, and which extends in the axial gap when the blade co-operates with the counter-pressure elements.       

     BACKGROUND TO THE INVENTION 
     Document EP-A-1 362 819 discloses a folding device for a rotary press which comprises a blade cylinder or cutting cylinder provided with a blade which is capable of cutting a printed web of material and a plurality of counter-pressure elements which co-operate with the blade and which are arranged so as to form axial gaps between each other. 
     Web traction belts extend in the axial gaps which serve to guide the printed web or the cut signature. The toothed belts comprise counter-pressure elements which are placed in the axial gaps. The blade also presses on the counter-pressure elements of the belts during the cutting operation. 
     This folding device has the disadvantage that the belts rapidly become damaged by the blade and must be changed regularly. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to overcome the disadvantage and provide a folding device which has longer maintenance intervals. 
     The present invention provides a folding device wherein the blade extends over the axial gap and the conveying element extends in the axial gap with spacing from the blade when the blade co-operates with the counter-pressure elements. 
     According to specific embodiments, the folding device comprises one or more of the following features:
         the axial width of the axial gap may be sufficiently small for the web to be cut by the blade in the entire zone corresponding to the axial gap;   the blade cylinder carries a plurality of blades being distributed over the circumference of the blade cylinder;   the blade cylinder including devices for gripping the cut signatures, for example, pincers;   the blade cylinder capable of being rotatably driven so that the peripheral speed of the blade cylinder is greater than the travel speed of the printed web of material;   the blade cylinder capable of being rotatably driven so that the peripheral speed of the blade cylinder is equal to the travel speed of the printed web of material;   the counter-pressure cylinder carries one assembly of counter-pressure elements;   the blade being retracted behind the covering surface of the blade cylinder, and the blade being surrounded by protection blocks being of rubber and capable of protecting the conveying element extending around the blade cylinder;   the conveying element includes at least a first belt provided with a transport surface being smooth directed towards the printed web of material during operation;   the first belt has a round or rectangular cross-section;   the first belt extends around the blade cylinder upstream of the cutting location and capable of retaining the web during the cutting operation;   a single bank of one or more first belts surrounding the counter-pressure cylinder and extending around the blade cylinder as far as a location for transfer of the signature, and the bank being capable of transporting the signatures from the cutting location to the transfer location;   the folding device comprises a first bank of belts constituted by a plurality of first belts surrounding the counter-pressure cylinder and are imbricated with a second bank constituted by second belts, the first and second belt banks capable of transferring a signature from the first belt bank to the second belt bank;   the second belt bank extends around the blade cylinder and capable of retaining the cut signatures on the surface of the blade cylinder, the speed of the belts of the second belt bank being identical to the tangential speed of the blade cylinder;   the folding device capable of driving each conveying element at a speed equal to or greater than the transport speed of the web; and   the folding device capable of driving each conveying element at a speed greater than the transport speed of the web and less than or equal to the transport speed of the signatures, and less than the transport speed of the signatures.       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be better understood from a reading of the following description, given purely by way of example and with reference to the appended drawings, in which: 
         FIG. 1  is a schematic side view of a folding device according to the present invention; 
         FIG. 2  is an enlarged view of a detail of  FIG. 1 ; 
         FIGS. 3 and 4  illustrate enlarged details of  FIG. 2 , during the different operating phases of the folding device; 
         FIG. 5  is a perspective view of a portion of the counter-pressure cylinder and the blade cylinder; 
         FIG. 6  is a side view of a detail of the blade cylinder and the counter-pressure cylinder, at the time of the cutting operation; 
         FIG. 7  is a schematic view of the conveying belts; and 
         FIGS. 8 and 9  are schematic side views of folding devices according to second and third embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       FIG. 1  illustrates a folding device  2  according to the invention. 
     The folding device  2  is capable of cutting and folding a printed web of material, such as a web of paper  4 . The web of paper  4  may have one or more layers. The web  4  is driven with a web speed V 1 . 
     The folding device  2  is equipped with two pairs of cylinders  6  and  8  for traction of the web  4 . The folding device  2  includes a blade or fold cylinder  10 , a counter-pressure cylinder  12 , a transfer cylinder  14  and two transfer cylinders  16  having pincers. 
     The folding device  2  is capable of cutting the web  4  into signatures  18  or sheets  18  and transporting the signatures/sheets with a signature speed V 2  which is preferably greater than the web speed V 1 . 
     To this end, the blade cylinder or fold cylinder  10  and the counter-pressure cylinder  12  together define a cutting location  19  which corresponds to the closest location between these two cylinders  10 ,  12 . Furthermore, the blade cylinder  10  has a peripheral speed which is equal to the signature speed V 2 . The rotation speed of the counter-pressure cylinder  12  is adapted to the speed of the blade cylinder  10  so that a counter-pressure element  26  is always present when a blade  20  presses on the web  4  in order to cut it. 
     The blade cylinder  10  includes three blades  20  being distributed regularly over the circumference of the cylinder  10 . The blades  20  are fixed to the blade cylinder  10  in a retracted position in which the cutting edge of the blade  20  is retracted behind the circumference of the cylinder  10 . Each blade  20  preferably extends in an uninterrupted manner over the entire axial width of the web  4  to be cut or the blade cylinder  10 . 
     For each blade  20 , the blade cylinder  10  is further provided with two protection blocks  22  of resilient material, such as rubber, which extend at one side and the other of the associated blade  20 . 
     Pincers  24  which are capable of holding cut signatures  18  are also arranged on the blade cylinder  10 . 
     The counter-pressure cylinder  12  includes one or more counter-pressure assemblies  25 , each of which is provided with a plurality of counter-pressure elements  26  which will be explained in greater detail below. 
     The folding device  2  is provided with a plurality of first conveying elements, in the form of a first bank of first belts  28  which extend around the counter-pressure cylinder  12 , which press on a segment of the surface of the blade cylinder  10  and on a segment of the surface of the counter-pressure cylinder  12 . These belts  28  are capable of conveying the web  4  and/or a cut signature  18  downstream of the cutting location  19 . Each first belt  28  comprises a round or rectangular cross-section and a smooth or slightly rough transport surface. This smooth surface reduces the soiling of the web. Each first belt  28  has a speed which is equal to or greater than the web transport speed V 1 . In a preferred configuration, the first belts  28  are driven at a speed which is greater than the web speed V 1 , and equal to or less than the signature speed V 2  and in particular strictly less than the signature speed V 2 . In this manner, the traction of the belts  28  on the web  4  and on the signatures  18  is limited and protects the paper. 
     The folding device  2  further includes a plurality of second conveying elements, in this instance, belts  30  which form a second bank of belts. As can be seen in  FIG. 7 , the belts  30  of the second belt bank are imbricated between the belts of the first belt bank  28  so that a signature head  18  can pass from the first belt bank  28  to the second belt bank  30 . The speed of the belts of the second belt bank  30  being identical to the peripheral speed of the blade cylinder  10 . 
     The protection blocks  22  are capable of contributing to protecting, on the one hand, the first belts  28  and, on the other hand, the second belts  30 , against wear by the blades  20 . 
     Furthermore, these protection blocks  22  keep the web  4  of paper pressed against the counter-pressure elements  26  at the time of the cutting operation. 
       FIG. 5  is a perspective view of a detail of the counter-pressure cylinder  12 . As can be seen, the counter-pressure elements  26  are arranged axially one behind the other in an aligned manner, together forming gaps  32  in which the first belts  28  engage during the cutting of the web of paper  4 . 
     Each counter-pressure assembly  25  extends axially along the counter-pressure cylinder  12 . 
     Each counter-pressure element  26  comprises a cutting groove  34  which extends axially and in which the blade  20  engages during the cutting operation. At each side of the groove  34 , there is arranged a support surface  36  which extends parallel with a tangent of the surface of the blade cylinder  10  and which receives the web of paper  4  under the action of the protection blocks  22  at the time of the cutting operation. Furthermore, the support surface  36  is displaced outwards relative to the surface of the blade cylinder  10 . Guiding grooves  40  are arranged in the counter-pressure cylinder  12 . These grooves  40  are aligned with the gaps  32  and extend circumferentially around the cylinder  12 . The belts  28  engage in these guiding grooves  40 . 
     As illustrated in  FIG. 6 , when the blade  20  presses in the bottom of the cutting groove  34  it extends through each axial gap  32  and the belt  28  extends in the gap  32  with a radial spacing e from the blade. This spacing is preferably 1 mm. In a variant, this spacing is between 0.5 mm and 1.5 mm. In this manner, the blade  20  is not in contact with the belt  28  during the entire cutting operation and the belt  28  is not damaged by this blade  20 . 
     Furthermore, the axial dimension of the gap  32  is selected so that the web  4  is cut by the blade  20  in the entire zone corresponding to the gap  32 . The web  4  is thus cut over the entire width thereof in a single operation. 
       FIG. 8  illustrates a second embodiment of the folding device according to the invention. This folding device  2  differs from that described above in the following manner. Elements which are similar have the same reference numerals. 
     The first belts  28  extend around a segment of the blade cylinder  10  upstream of the cutting location  19 , and are capable of retaining the web  4  in a zone which extends upstream from the cutting location at the time of the cutting operation. In this manner, the end of the web  4  that is created by the cutting operation is retained. Furthermore, the first belts  28  completely surround the counter-pressure cylinder  12  and are deflected by three deflection rollers  50 . Consequently, the first belts  28  are in contact with the counter-pressure cylinder  12  only in the zone defined by the counter-pressure elements  26  or are not in contact over the entire circumference of the counter-pressure cylinder  12 . 
     This embodiment facilitates the driving of the first belts  28  at a speed V 3  which is different from the web speed V 1  or the signature speed V 2 . 
     The second belts  30  are not illustrated in this Figure. 
       FIG. 9  illustrates a third embodiment of the folding device according to the invention. 
     This folding device  2  differs from the folding device described above in the following manner. 
     The first belts  28  press, downstream of the cutting location  19 , against the blade cylinder  10  on a segment which corresponds to approximately 170°, that is to say, as far as a location for transferring the signature  18  to the transfer cylinder  14 . The belts  28  thus extend around three return rollers  50 . 
     Owing to this embodiment, the second belts  30  may be omitted whilst providing correct guiding of the cut signature  18  as far as the region of the transfer cylinder  14 . 
     In a variant which is not illustrated, the counter-pressure pressure cylinder  12  carries a plurality of counter-pressure assemblies  25  or counter-pressure elements  26  which are distributed over the circumference thereof. 
     During operation, the blade cylinder  10  is capable of being rotatably driven so that the peripheral speed thereof is greater than the travel speed V 1  of the printed web  4  of material and is equal to the speed V 2 . 
     In a variant, the blade cylinder  10  is capable of being rotatably driven so that the speed thereof is equal to the travel speed V 1  of the printed web  4  of material. In this instance, the speed V 2  is equal to the speed V 1 . 
     Preferably, the counter-pressure assembly  25  and therefore the counter-pressure elements  26  are produced as a single component, the gap  32  between two counter-pressure elements being formed by a recess or a groove for guiding the belts  28 . This variant facilitates the assembly and the production of the folding device. 
     Furthermore, the cutting groove  34  may be omitted. 
     It is self-evident that the belts  28  may be replaced with another conveying element, for example, a chain.