The present invention is related to an knife assembly which is integrated into a rotating surface travelling about an endless path.
U.S. Pat. No. 5,107,733 is related to an apparatus for cutting and transporting a paper web in a folding apparatus of the 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 anvil and the second cutting cylinder has at least one cutting knife which meets the cutting anvil 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 positions 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. In this known solution, said knife assembly is integrated into grooves assigned to a cutting cylinder of a pair of cutting cylinders.
U.S. Pat. No. 5,186,444 is related to 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 layer structure formed of mutually super-imposed web surface portions along respective strips thereof, a plurality of tongue-like elements remain appendant to the web surface portions and projecting through respective holes simultaneously stamped 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. Again in this known solution, cutting knife assemblies are assigned to a pair of cutting cylinders integrated into grooves laterally extending on the surface of the respective cutting cylinder.
There is a need to enhance cutting performance by constraining the incoming web of material prior to the cutting operation and after the cutting operation. Several attempts have been undertaken to improve cutting performance by using other materials, to improve the geometry of the device, and improve cutting dynamics. Attempts have been made to use electrostatic tackers and to corrugate the signature in order to stiffen it appropriately.
In view of the prior art and the problems encountered in the technical field it is accordingly an object of the present invention to constrain signatures upon creation and during transport out of the cutting region.
A further object of the present invention is to provide for a cyclic activation of cutting elements integrated into a revolving transport system.
According to the present invention an apparatus for cutting webs of material includes a first revolving member, a second revolving member having cutting elements integrated therein, said revolving members defining a cutting region therebetween, and supporting elements assigned to said revolving elements within said cutting region.
Advantageous with the present invention is the elimination of relative movements of the created signature after being severed from the incoming web; there are no more relative movements between the cut signature and the transport belt. The signature severed will be forwarded in a precise position to further downstream transport systems. By having a supporting element assigned to said revolving members, it is ensured that cooperating knives and anvils are supported upon a cutting operation to obtain a precise lateral cut and a high quality signature.
According to further details of the present invention, said first revolving member is a transport belt revolving about an endless loop. Said second revolving member is a layered structure, discussed in greater detail below and likewise revolving about an endless loop. To provide for a support of said first and second revolving members rotating supporting elements are tied in to an endless loop, the revolving members moving about deviation rollers. Said second revolving member comprises openings, through which each cutting element being integrated into the layered structure thereof protrudes and severs a signature upon a cutting operation.
Said first and second revolving members, respectively, have a multi component structure. Said first revolving member may comprise a plurality of laterally extending cut rubber portions, mounted into laterally extending grooves in said belt-shaped first revolving member. Said second revolving member may include a belt assembly comprising a substrate base layer. Said substrate base layer either may have a flat surface for contacting a rotating supporting element or may be shaped as a toothed surface contacting said outer circumference of said supporting element upon a cutting operation. Said substrate base layer may comprise a reinforcing member, which extends into longitudinal direction of said substrate base layer, i.e. parallel to the transport direction of said signature. A reinforcing member may be shaped as a cord or as fibres, such as Kevlar fibres.
Said second revolving member having a multi layered structure includes a mounting groove for said cutting elements which may be shaped as a T-slot, or a lateral groove for a knife base of the respective cutting element. Said mounting groove either may be arranged on top of said substrate layer, or on the bottom thereof to receive the respective knife base for ensuring safe mounting of said cutting elements. On top of said substrate layer a compressible layer may be arranged, being compressible upon contact with an opposite surface allowing for protrusion of said cutting elements integrated into said second revolving member.
The cutting elements may be shaped as having a spring-like base which allows for a protruding movement of said knife tip upon contact of the knife base with the respective surface of said second supporting element being integrated into the endless loop of said second revolving member.