Abstract:
The present invention is related to an apparatus for cutting webs of material ( 1 ) and includes a cutting cylinder ( 8 ) having at least one knife assembly ( 12, 13 ) assigned to its circumference ( 9 ). A supporting element ( 23 ) is assigned to said cutting cylinder ( 8 ) forming a cutting region ( 3 ) there between and a transport belt ( 20 ) having cut rubber portions ( 20.1, 20.2, 20.3 ) integrated therein is assigned to said supporting element ( 23 ).

Description:
FIELD OF THE INVENTION 
     The present invention is related to a cutting rubber assembly which requires low maintenance and which can be used in machines that cut webs of any sort. 
     BACKGROUND OF THE INVENTION 
     U.S. Pat. No. 5,107,733 is related to an apparatus for cutting and transporting a paper web in a folding apparatus of a printing press. An apparatus for transporting a web in a printing press comprises a pair of cutting cylinders for cutting web sections from the web, and a transporting device for transporting the web sections away from the cutting cylinders. The first cutting cylinder has at least one cutting angle and the second cutting cylinder has at least one cutting knife which meets the cutting angle at a nip between the cutting cylinders, to cut the web moving through the nip. A plurality of strips are supported on the first cutting cylinder and a plurality of strips are supported on the second cutting cylinder. The strips have positioned on the cutting cylinders in which they impress a temporary reinforcing profile onto each newly formed leading portion of the web, when the strips move through the nip. At least one smoothing surface is supported on the first cutting cylinder and at least one smoothing surface is supported on the second cutting cylinder. The smoothing surfaces have positions on the cutting cylinders, wherein the smoothing surfaces remove the temporary reinforcing profile from the leading portion of the web, when the smoothing surfaces move through the nip. 
     U.S. Pat. No. 5,186,444 concerns a method and device for assuring orderly web travel in a folder by punching holes in a paper width direction. 
     A method of assuring orderly web travel in a folder includes stamping out of a layer structure formed of mutually superimposed web surface portions, along respective strips thereof, a plurality of tongue-like elements remaining appendant to the web surface portions and projecting through respective holes simultaneously stand out of the web surface portions, so as thereby to hold the web surface portions together at the respective strips thereof and a device for performing the method. 
     The known devices according to the prior art have anvil bars which are assigned to lateral grooves of the anvil cylinders. Once said anvil bars consisting essentially of rubber are worn out, they have to be exchanged. Maintenance regarding the exchange of anvil bars on cutting cylinders requires considerable down time of the press. Further, the accessibility of said anvil bars is difficult. 
     A further disadvantage of the rectangular shaped anvil bars known from the art is that they constrain the signature on impact of the knife and cheekwood of the assembly upon the cutting operation only. Prior to and after the cut operation a signature constraint cannot be achieved with device known from the art. 
     SUMMARY OF THE INVENTION 
     In view of the prior art cited it is an object of the present invention to reduce the maintenance of cutting rubbers. 
     A further object of the present invention is to improve the constraint on the signature as it is created. 
     According to the present invention, an apparatus for cutting webs of material includes: 
     a cutting cylinder having at least one knife assembly assigned to its circumference, 
     a supporting element assigned to said cutting cylinder forming a cutting region there between, and 
     a transport belt having integrated cut rubber portions, said transport belt being assigned to said supporting element. 
     The present invention offers the advantage to index said belt upon wear of the cut rubber spot to a fresh cut rubber spot or portion, respectively. When there are no more fresh spots, the entire belt can be replaced very easily. Furthermore, a constraint is exerted upon the incoming web and the signature resulting there from over the entire length of the cutting region, prior to the cutting region and behind the cutting region. 
     According to further details of the present invention, said transport belt travels along an endless loop about said supporting element which may be designed as an anvil cut roller or cylinder with a smooth surface. Said revolving transport belt co-operates with an upper web transport device prior to the cutting region as well as with a lower signature transport device. Said transport belt is substantially supported by a supporting element within said cutting region, i. e. upon its section of the travel path opposite said knife cylinder. Said transport belt having cut rubber portions assigned thereto, bridges the distance between said upper web transport device and said lower signature transport device. The width of said transport belt corresponds to the maximum width of the web to be processed in a folder apparatus arranged behind a rotary printing press. 
     On the transport belt a laminated cut rubber layer may be provided, the cut rubber layer traveling with the transport belt about its closed loop. Upon wearing of a spot of the laminated cut rubber layer, the transport belt is indexed, so that a new spot of the respective cut rubber layer co-operates with respective knife assemblies upon a cutting operation. As an alternative, distinct cut rubber portions may be integrated into the transport belt received in lateral grooves assigned to said transport belt. Upon the occurrence of a cut operation, said spot of the cut rubber layer or said distinct cut rubber portions received by a lateral groove are supported by said supporting element, being an anvil roller having a smooth surface for instance. 
     Along the entire surface of said transport belt adjacent cut rubber portions may be arranged so as to provide several fresh cutting anvils which are easy to replace upon wear. 
     The present invention further discloses a method for severing signatures from an incoming web of material comprising the steps of 
     constraining an incoming web of material between a transport belt and a signature transport device, 
     supporting said transport belt having cut rubber portions integrated therein by a supporting element upon impact of a knife assembly, and 
     constraining the severed signature between a portion of said transport belt and a signature transport device upon further travel of the severed signature in signature travel direction. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The present invention itself, however, both as to its construction and its method of operation together with additional objects and advantages thereof will be best understood from the following description of a specific embodiment when read in connection with the accompanying drawings in which: 
     FIG. 1 shows an existing cutting cylinder pair design, the anvil cylinder having anvil bars assigned thereto; 
     FIG. 2 shows a transport belt having cutting rubber portions assigned thereto, shown in regions A and B; and 
     FIGS. 2A and 2B show the regions A and B of FIG. 2 in greater detail. 
     FIG. 3 shows a 3-dimensional view of a cutting cylinder having a plurality of cams integrated therein. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIG. 1 shows an existing cutting cylinder pair design with the anvil cylinder having anvil bars assigned thereto. 
     An incoming web of material  1  is forwarded into a cutting region  3  by a pair of nip rollers  2  arranged above a cutting cylinder pair, including an anvil cylinder  4  and a knife cylinder  8 . Knife cylinder  8  includes two knife assemblies, a first knife assembly  12  and a second knife assembly  13 . Between said first and second knife assembly  12 ,  13 , respectively, surface jackets  10  are assigned to the circumference  9  of said knife cylinder  8 . Said first and second knife cylinder assemblies  12 ,  13 , respectively, are arranged opposite to one another, thus severing two signatures from the incoming web of material  1  upon a complete revolution. Said anvil cylinder  4  has two rectangularly shaped anvil bars, a first anvil bar  6  and a second anvil bar  7  cooperating with said first and second knife assemblies  12 ,  13  respectively, of said knife cylinder  8 . Said first and second anvil bars  6 ,  7  respectively, are arranged opposite to one another. Within a cutting region  3  signatures  15  are severed from said incoming web of material  1 , said signatures  15  being transferred to a transporting system including a left transport system  16  and a right transport system  18 . Both transport systems  16 ,  18 , respectively, have revolving belts  17  assigned thereto for further transportation of said signatures  15 , continuously severed from the incoming web of material  1  in said cutting region  3 . 
     FIG. 2 shows a transport belt having rubber portions assigned thereto, while FIGS. 2A and 2B show the regions A and B respectively of FIG. 2 in greater detail. 
     According to the present invention, above a knife cylinder  8  constraining tapes  19  are arranged which cooperate with a transport belt  20 . Said transport belt  20 , extending over the width of said knife cylinder  8 , corresponds in its width to the maximum width of the web of material  1  to be processed in a folding apparatus, for example. Said transport belt  20  travels along an endless loop, not shown in greater detail here and substantially extends in its vertical path from said constraining tapes  19  through said cutting region  3  to a signature its vertical path from said constraining tapes  19  through said cutting region  3  to a signature transporting device  24  arranged below said knife cylinder  8 . As previously has been mentioned, two knife assemblies  12 ,  13 , respectively, are assigned to the circumference  9  of said knife cylinder  8  opposite to one another. Besides the knifes for severing a signature  15  from the incoming web of material  1 , said knife assemblies  12 ,  13  comprise cheekwoods  22  for securing said knifes to the respective knife assembly  12 ,  13 , respectively. Still further, cams  28  are arranged within said knife cylinder  8 , which are mounted pivotally about respective axes  27 . Said axes  27  extend substantially through the interior of said knife cylinder  8 . Said cams  28  each comprise a cam surface  29  including a respective contacting portion  30 . Further, said cams  28  are connected to spring means  31  retracting said cams  28  into its respective disengaged position within circumferential grooves of said knife cylinder  8 . In its engaged position said cams  28  contact with respective contacting portions  30  trailing edges of cut signatures  15  leaving said cutting region  3 . It can be derived from Fig. 2 of the present application that said cam surfaces  29  penetrate said surface  9  of said knife cylinder in the respective section of the cylinders surface  9  below said respective knife assembly  12 ,  13 , respectively. Said contacting portions  30  exactly will seize the trailing edge of cut signature  15  once this signature  15  has left the cut region  3 , i. e. a constraint on the signature  15  is exerted upon leaving the cutting region  3 . 
     Opposite said knife cylinder  8 , a revolving supporting element  23  is arranged, having a substantially flat surface on its circumference  23 . 1 . Said supporting element  23  supports said transport belt  20  upon a cutting operation in the cutting region  3  and supports the new formed leading edge of said incoming web of material  1  until the next cutting operation occurs. The cut signature  15  is forwarded to a signature transporting device  24  cooperating with said transport belt  20  travelling in direction  26  of signature travel. 
     The operation of the improved design according to the present invention will be described in greater detail below. 
     An incoming web of material  1  to be processed will be seized between said transport belt  20  and said constraining tapes  19  prior to said region  3 . A leading edge of said incoming web  1  will pass the cutting region  3  until the next knife assembly  12  or  13  will approach the cutting region  3  travelling on said circumference  9  of said knife cylinder  8 . Since the cutting operation requires an anvil counter part to perform a distinct precise cut of a web of material or a package of a multilayered web ribbon, upon a cut, said transport belt  20  is supported by revolving supporting element  23 , such as an anvil roller or an anvil cylinder. Said supporting element  23  is provided with a flat surface  23 . 1  and is intended to support the transport belt  20  upon the occurrence of a cutting operation. However, the counter part for the cutting operation, i. e. the cut rubber contacting the tip of the knife, is integrated into said transport belt  20 . FIGS. 2A and 2B show two more detail of the areas A and B in FIG. 2, and thus show two possible alternatives for the structure of the belt  20 . 
     FIG. 2A shows said transport belt  20  having a rubber layer  20 . 1  laminated thereto and said transport belt  20  travelling in signature travel direction  26 . A spot of said cut rubber layer  20 . 1  will form the respective counter part or anvil for a respective tip of a knife of said knife assemblies  12  and  13 , respectively, assigned to said circumference  9  of said knife cylinder  8 . In a second embodiment said transport belt  20  comprises lateral extending grooves  21  each receiving cut rubber portions  20 . 2  and  20 . 3  as shown in FIG.  2 B. Again, said transport belt  20  moves into signature travel direction indicated by arrow  26 . In the second orientation shown in FIG. 2B, the drive of said transport belt  20  may be synchronized such that upon occurrence of a cutting operation a respective one of said cut rubber portions  20 . 1 ,  20 . 3  respectively is arranged opposite the approaching knife assembly  12 ,  13 , respectively, performing a cut and severing a respective signature  15  from the web of material. 
     Upon severing of a signature  15  from the incoming web of material  1 , said signature  15  upon further travel through said cutting region  3  is supported by said transport belt  20 , traveling in signature conveying direction  26 . Thus, upon further travel of the cut signature  15 , the constraint on the signature  15  is improved by having said contacting surfaces  29  of the respective cams  28  contact said leading edge of the cut signatures  15 . Thus, upon further travel of said cut signature  15  to said further transport device  24 , said cut signatures are seized upon transport. Said cut signature  15  will be seized between said transport belt  20  and a revolving seizing or transport belt  24  of said signature transport device downstream of said cutting region  3  after said contacting surfaces  30  have released the respective trailing edge of said cut signature  15 . Said cams  28  are actuated by mechanical cam followers, an air or hydraulic cylinder, by means of electronic solenoids, stepper motor, magnetic flux, or an inflatable bladder. Said transport device  24  may include a deviation roller  25 , only schematically given in FIG. 2 of the present application. 
     Suitable materials for said laminated cut rubber layer  20 . 1  or the shaped cut rubber portions  20 . 2 ,  20 . 3  are materials such as urethane or polyurethane. 
     Said revolving transport belt  20  may include said cut rubber portions  20 . 2  and  20 . 3 , respectively, arranged adjacent to one another across the entire length of said transport belt  20 . Said laminated cut rubber layer  20 . 1  shown in FIG. 2A is provided along the entire length of said transport belt  20 . If, after numerous cutting cycles, the respective spot of the laminated cut rubber layer  20 . 1  is worn out, the transport belt  20  will be indexed to arrange a fresh spot vis-a-vis the respective knife of the knife assemblies  12 ,  13 , respectively. With the embodiment of FIG. 2B, if the transport belt  20  has worn out rubber portions  20 . 2 ,  20 . 3  assigned to lateral grooves  21 , said transport belt  20  will be indexed to the next available fresh cut rubber portion  20 . 2 ,  20 . 3 . 
     Thus, maintenance is reduced to an indexing operation to be performed on said transport belt  20 , once the cutting quality becomes insufficient. An entire replacement of said transport belt  20  according to the present invention will be due only after many indexing operations. In the designs according to the prior art, a replacement of the rectangular shaped anvil bars directly assigned to the anvil cylinder causes considerable downtime of the machine. 
     FIG. 3 of the present application disclose a 3-dimensional view of a knife cylinder  8  according to the present invention. 
     Across the width of said knife cylinder  8  a plurality of circumferential grooves  32  is provided in which said pivotally mounted cams  28  are arranged. Said cams  28 , each having a cam surface  29  and a respective contacting portion  30  are mounted such that said cam surfaces  29  penetrate a respective surface  9  of said knife cylinder  8  below said knife assemblies  12 ,  13  respectively. As can be derived from the perspective view given in FIG. 3, said contacting portions  30  of said cam surfaces  29  interlace with said belt roller about which said belts  24  rotate. For reasons of clarity said transport belt  20  is not shown in the perspective view of said knife cylinder  8  according to FIG.  3 . Across the width of said knife cylinder  8  a pivot axis  27  extends about which said cams  28  are rotatably mounted. Said knife assemblies  12 ,  13 , respectively each comprise a knife extending parallel to the axis of rotation of said knife cylinder  8 . Said knife is mounted between two cheekwoods  22  of the respective knife assemblies  12 ,  13 . 
     List of Parts 
       1  incoming web 
       2  pair of nip rollers 
       3  cutting region 
       4  anvil cylinder 
       5  anvil cylinder surface 
       6  first anvil bar 
       7  second anvil bar 
       8  knife cylinder 
       9  circumference 
       10  surfacejacket 
       11  axis of rotation 
       12  first knife assembly 
       13  second knife assembly 
       15  cut signature 
       16  left transport system 
       17  belt 
       18  right transport system 
       19  constraining tapes 
       20  transport belt 
       20 . 1  cut rubber layer 
       20 . 2  cut rubber portion 
       20 . 3  cut rubber portion 
       21  cut rubber groove 
       22  cheekwood 
       23  supporting element 
       23 . 1  supporting element circumference 
       24  belt 
       25  deviation roller 
       26  direction of signature travel 
       27  pivot axis 
       28  cam 
       29  cam surface 
       30  contacting portion 
       31  spring means 
       32  circumferential groove